In this article you can learn how to delete screen time data.
Here you can learn how to turn off restrictions on iPad.
Here you can learn 3 effective methods to remove device supervision on iPad.
Here you can learn how to bypass MDM lock on iOS 14/15.
Here is the full guide on how to solve the most common iOS restore and update issues.
There are three ways of to fix "how to get rid of someone else's Apple ID on my iPhone", when you have a transferred device and you can contact the previous owner.
To fully reset your iPad, if you forgot your password, you would be able to use a different variety of resources such as WooTechy, iCloud, and iTunes.