If the "Turn off professional mode" button is missing from your Facebook profile menu, here are a few steps you can try:

1. Update the App: Ensure that you are using the latest version of the Facebook app. Outdated versions can sometimes cause features to be missing or not function correctly.

2. Check on a Different Device: Try accessing your Facebook account from a different device or browser to see if the option is available there.

3. Clear Cache and Cookies: Clearing the cache and cookies of your browser or app might resolve the issue.

4. Account Settings: Navigate through the account settings carefully to ensure you haven't missed the option. Sometimes, the option might be located in a different sub-menu.

5. Contact Support: If the option is still missing, consider reaching out to Facebook support for assistance. They can provide specific guidance or fix any potential issues with your account.

Facebook frequently updates its features and interface, so it’s possible that the option has been moved or temporarily removed. Checking Facebook’s help center or forums might also provide more current solutions. Thanks. Mahamudul Hasan.