Can’t access Apple ID and gmail connected to it

Hello. A problem with my iPad 2. It wasn’t in use so it got to recovery mode, but I managed to restore and update it. But the device is connected to my old Apple ID, and it to is connected with my old gmail, but my gmail is now deleted (for good) and I can’t use it to unblock Apple ID and delete the device from it.

How can I delete my old Apple ID or detach iPad from this Apple ID?

Help please. Thank you very much.