diff --git a/packages/api/src/router/testSupport/prepareUser.ts b/packages/api/src/router/testSupport/prepareUser.ts
index ce7a8b544..05ddc42c3 100644
--- a/packages/api/src/router/testSupport/prepareUser.ts
+++ b/packages/api/src/router/testSupport/prepareUser.ts
@@ -1,4 +1,5 @@
 import { clerkClient } from "@clerk/nextjs/server";
+import { isClerkAPIResponseError } from "@clerk/shared";
 import { aiLogger } from "@oakai/logger";
 import { waitUntil } from "@vercel/functions";
 import os from "os";
@@ -75,24 +76,50 @@ const generateEmailAddress = (personaName: keyof typeof personas) => {
   return `${parts.join("+")}@thenational.academy`;
 };
 
-const deleteLastUsedTestUser = async () => {
-  const users = await clerkClient.users.getUserList({
-    orderBy: "+last_active_at",
+const deleteOldTestUser = async () => {
+  const result = await clerkClient.users.getUserList({
     limit: 500,
   });
 
   const NUMBERS_USER = /\d{5,10}.*@/; // jim+010203@thenational.academy
-  const lastUsedTestUser = users.data.find((u) => {
+  const testUsers = result.data.filter((u) => {
     const email = u.primaryEmailAddress?.emailAddress ?? "";
     return email.startsWith("test+") || email.match(NUMBERS_USER);
   });
 
-  if (lastUsedTestUser) {
-    log.info(
-      "Deleting oldest test user",
-      lastUsedTestUser.primaryEmailAddress?.emailAddress,
-    );
-    await clerkClient.users.deleteUser(lastUsedTestUser.id);
+  if (testUsers.length < 100) {
+    log.info(`less than 100 test users. Skipping cleanup.`);
+    return;
+  }
+
+  const users = testUsers.sort(
+    (a, b) =>
+      new Date(a.lastActiveAt ?? a.createdAt).getTime() -
+      new Date(b.lastActiveAt ?? b.createdAt).getTime(),
+  );
+
+  // If multiple personas are created at the same time and both try to delete the
+  // oldest user they will conflict. Add some randomness to reduce conflicts
+  const randomOffset = Math.floor(Math.random() * 8);
+  const userToDelete = users[randomOffset];
+
+  if (userToDelete) {
+    try {
+      await clerkClient.users.deleteUser(userToDelete.id);
+      log.info(
+        "Deleted old test user",
+        userToDelete.primaryEmailAddress?.emailAddress,
+      );
+    } catch (e) {
+      if (isClerkAPIResponseError(e) && e.status === 404) {
+        log.info(
+          `${userToDelete.primaryEmailAddress?.emailAddress} already deleted, retrying`,
+        );
+        deleteOldTestUser();
+      } else {
+        throw e;
+      }
+    }
   }
 };
 
@@ -134,7 +161,7 @@ const findOrCreateUser = async (
     },
   });
 
-  waitUntil(deleteLastUsedTestUser());
+  waitUntil(deleteOldTestUser());
 
   return newUser;
 };