Originally Posted by
iOS Gravity You can remotely wipe the iPad or use your phone number for iMessages.
If there was no passcode set on the iPad before, you can lock it with a new passcode of your choice via find my iPad. There is no need to wipe it as my fellow forum member says. However if there was already a passcode set on the iPad, then there is no other choice other than wiping it.
Maybe you can call your parents and ask them to disable iMessage in settings. There is a slight chance they will do as you said.
You also can threaten your dad with a lawsuits if he continues violating your privacy