How do I stop using hide my email?

Go to settings, very top is your Apple ID, click they, then a few rows down is iCloud, click that snd you’ll see hide my emdil. Click it snd you’ll see the list of all the hides you’re using. If there isn’t a bunch you can delete one by one.

otherwise you can log into Apple ID on a browser and cancel all places you’re signed in with apple be it actual or hide my emails.

I don't believe you can turn it off.. but when you are creating new accounts or entering your email address, just don't select Hide My Email..

You will find a list of those you have already created in Settings > [your name] > iCloud > Hide My Email

You can delete those, but you are potentially also deleting sign in credentials (particularly if it was created using Sign In with Apple?) for those websites.. if that matters to you.