How do you completely clear user data on logout?

Short answer

Revoke all tokens from secure storage (SecureStore/Keychain), clear cached data in MMKV and QueryClient, and reset global state stores (Zustand/Redux) to their initial state.

Explanation

Failing to clear data on logout is a serious security risk: the next user on the same device could see the previous user's cached messages or data. Create a centralized cleanup function that runs storage.clearAll(), SecureStore.deleteItemAsync(), and queryClient.clear() together.

Code example

async function handleUserLogout() {
  // 1. Clear encrypted authentication tokens
  await SecureStore.deleteItemAsync('auth_token');
  // 2. Clear the cache for API
  queryClient.clear();
  // 3. Reset state stores
  useUserStore.getState().reset();
  // 4. Delete fast local storage
  storage.clearAll();
}

Common mistakes

• Only clearing the token from in-memory state without deleting it from persistent storage or clearing query caches.

Follow-up questions

• How do you manage local and remote push notifications and their tokens?
• How do you use Zustand with MMKV to create a synchronous global state store persisted locally?

Sources

• React Native docs — Security
• TanStack Query docs — QueryClient