diff --git a/packages/gateway/public/admin.html b/packages/gateway/public/admin.html
index 4a19e43..a25bcb1 100644
--- a/packages/gateway/public/admin.html
+++ b/packages/gateway/public/admin.html
@@ -636,13 +636,16 @@ <h2>Tool catalog <span class="muted">${enabledCount} of ${tools.length} enabled
   el.innerHTML = `
     <section class="panel"><h2>Users (OIDC logins)</h2>
       ${users.length ? `<table>
-        <tr><th>User</th><th>Subject</th><th>Last login</th><th>Role</th></tr>
+        <tr><th>User</th><th>Subject</th><th>Last login</th><th>Role override</th><th>From groups</th><th></th></tr>
         ${users.map(u => `<tr>
           <td>${esc(u.displayName || u.email || "—")}</td>
           <td class="mono">${esc(u.email || u.sub)}</td>
           <td class="muted">${esc(u.lastLoginAt || "")}</td>
           <td><select data-user="${u.id}">${roleOpts(u.roleId)}</select></td>
-        </tr>`).join("")}</table>` : '<p class="muted">No OIDC logins yet.</p>'}
+          <td class="muted">${u.loginRoles?.length ? esc(u.loginRoles.join(", ")) : "—"}</td>
+          <td><button class="btn danger" data-del-user="${u.id}" data-del-user-label="${esc(u.email || u.sub)}">Delete</button></td>
+        </tr>`).join("")}</table>
+        <p class="muted" style="margin:8px 0 0">An override wins over groups; with none, access is the <b>union</b> of every mapped group's role. Deleting a user forgets their row, prefs, credential refs and sessions — it does not revoke access, since a mapped group brings them back at the next login.</p>` : '<p class="muted">No OIDC logins yet.</p>'}
     </section>
     <section class="panel"><h2>Group → role mappings</h2>
       ${mappings.length ? `<table>
@@ -678,6 +681,20 @@ <h2>Tool catalog <span class="muted">${enabledCount} of ${tools.length} enabled
           <td><button class="btn danger" data-del-client="${esc(c.clientId)}">Delete</button></td>
         </tr>`).join("")}</table>` : '<p class="muted">No registered clients.</p>'}
     </section>`;
+  el.addEventListener("click", async (ev) => {
+    const b = ev.target.closest("[data-del-user]");
+    if (!b) return;
+    const label = b.dataset.delUserLabel;
+    if (!confirm(`Forget ${label}?
+
+Removes their row, personal prefs, credential refs and live sessions. It does NOT revoke access: if a mapped group still contains them, they return at the next login.`)) return;
+    try {
+      const r = await api(`/users/${b.dataset.delUser}`, { method: "DELETE" });
+      toast(`Deleted ${label} — ${r.prefs} pref(s), ${r.credentials} credential ref(s), ${r.sessionsClosed} session(s)`);
+      if (r.note) toast(r.note);
+      renderUsers();
+    } catch (e) { toast(e.message, true); }
+  });
   el.onchange = async (ev) => {
     const s = ev.target; if (!s.dataset.user) return;
     try {
diff --git a/packages/gateway/src/db/repo.ts b/packages/gateway/src/db/repo.ts
index fbcb0d2..df987ae 100644
--- a/packages/gateway/src/db/repo.ts
+++ b/packages/gateway/src/db/repo.ts
@@ -427,6 +427,45 @@ export class Repo {
     ).map(mapUser);
   }
 
+  /**
+   * Remove a user row and everything keyed to that identity: group-derived
+   * roles (FK cascade), personal prefs, credential REFS, and any live refresh
+   * tokens. Deliberately NOT an access revocation — someone still in a mapped
+   * group simply gets a fresh row at their next login; this is for clearing
+   * accounts that will never come back (a stale admin login, a departed user).
+   * Secret-store values behind the credential refs are not touched (issue #9).
+   */
+  deleteUser(userId: number): { principal: string; prefs: number; credentials: number; refreshTokens: number } | null {
+    const user = (this.db.prepare("SELECT id, iss, sub FROM users WHERE id = ?").get(userId) ?? null) as
+      | { iss: string; sub: string }
+      | null;
+    if (!user) return null;
+    const principal = `oidc:${user.iss}|${user.sub}`;
+    this.db.exec("BEGIN");
+    try {
+      const prefs = this.db.prepare("DELETE FROM user_prefs WHERE principal = ?").run(principal).changes;
+      const credentials = this.db
+        .prepare("DELETE FROM user_credentials WHERE principal = ?")
+        .run(principal).changes;
+      const refreshTokens = this.db
+        .prepare(
+          "UPDATE oauth_refresh_tokens SET revoked_at = datetime('now') WHERE principal_iss = ? AND principal_sub = ? AND revoked_at IS NULL"
+        )
+        .run(user.iss, user.sub).changes;
+      this.db.prepare("DELETE FROM users WHERE id = ?").run(userId);
+      this.db.exec("COMMIT");
+      return {
+        principal,
+        prefs: Number(prefs),
+        credentials: Number(credentials),
+        refreshTokens: Number(refreshTokens),
+      };
+    } catch (err) {
+      this.db.exec("ROLLBACK");
+      throw err;
+    }
+  }
+
   /** Admin/bootstrap override — REPLACES whatever the user's groups map to. */
   setUserRole(userId: number, roleId: number | null): boolean {
     const result = this.db
diff --git a/packages/gateway/src/http/admin-api.ts b/packages/gateway/src/http/admin-api.ts
index 2ada367..16965b4 100644
--- a/packages/gateway/src/http/admin-api.ts
+++ b/packages/gateway/src/http/admin-api.ts
@@ -540,6 +540,37 @@ export function createAdminRouter(deps: AppDeps, admin: AdminDeps): Router {
     })
   );
 
+  /**
+   * Forget a user: the row, their group-derived roles, personal prefs,
+   * credential refs, refresh tokens, and any live session. NOT a revocation —
+   * anyone still in a mapped group returns on their next login — so the
+   * response says what actually happened rather than implying more.
+   */
+  router.delete(
+    "/users/:id",
+    h((req, res) => {
+      const removed = repo.deleteUser(Number(param(req, "id")));
+      if (!removed) {
+        res.status(404).json({ error: "Unknown user" });
+        return;
+      }
+      const sessionsClosed = admin.reloadSessions(
+        (session) => prefsIdentity(session.principal) === removed.principal
+      );
+      admin.onPolicyChanged();
+      console.error(`[admin] deleted user ${removed.principal} (${sessionsClosed} session(s) closed)`);
+      res.json({
+        ok: true,
+        ...removed,
+        sessionsClosed,
+        note:
+          removed.credentials > 0
+            ? "Credential refs removed; the values still exist in the secret store and need deleting there."
+            : undefined,
+      });
+    })
+  );
+
   router.get(
     "/group-mappings",
     h(async (_req, res) => {
diff --git a/packages/gateway/src/http/app.test.ts b/packages/gateway/src/http/app.test.ts
index d15af3e..8c96e54 100644
--- a/packages/gateway/src/http/app.test.ts
+++ b/packages/gateway/src/http/app.test.ts
@@ -625,6 +625,37 @@ describe("session reload", () => {
   });
 });
 
+describe("forgetting a user", () => {
+  it("removes the row and everything keyed to that identity, and 404s twice", async () => {
+    const user = repo.upsertUserOnLogin({ iss: "https://idp", sub: "gone", email: "gone@test" });
+    const principal = "oidc:https://idp|gone";
+    repo.setUserPref(principal, "fake", "read_thing", false);
+    repo.setLoginRoles(user.id, [repo.roleByName("viewer")!.id]);
+
+    const del = async () =>
+      fetch(`${base}/api/users/${user.id}`, {
+        method: "DELETE",
+        headers: { Authorization: "Bearer tok-admin" },
+      });
+
+    expect((await del()).status).toBe(200); // idempotent-ish: the second try 404s
+    expect(repo.listUsers().some((u) => u.sub === "gone")).toBe(false);
+    expect(repo.listUserPrefs(principal)).toHaveLength(0);
+    expect(repo.loginRoles(user.id)).toHaveLength(0);
+    expect((await del()).status).toBe(404);
+  });
+
+  it("is admin-only", async () => {
+    const user = repo.upsertUserOnLogin({ iss: "https://idp", sub: "keep-me" });
+    const asViewer = await fetch(`${base}/api/users/${user.id}`, {
+      method: "DELETE",
+      headers: { Authorization: "Bearer tok-viewer" },
+    });
+    expect(asViewer.status).toBe(403);
+    expect(repo.listUsers().some((u) => u.sub === "keep-me")).toBe(true);
+  });
+});
+
 describe("bulk catalog toggle", () => {
   const bulk = (body: unknown, upstream = "fake") =>
     fetch(`${base}/api/catalog/${upstream}`, {