How do I deregister Imessages on Android?

Turn off iMessage

Tap Messages. Set iMessage to Off.

How do I disassociate my phone number from iMessage?

Go to Settings app on your iPad and then tap on Messages option. Tap on Send & Receive option. Now, you can find your number in iMessage settings below “You can be reached by…” section and uncheck your phone number. This will remove your phone number from iMessage.