How to disconnect an apple device from your account permanently?

So I gave my old iPod Touch (4th Gen) to my cousin, to have. I deleted my iCloud from the device, but recently, he was texting a friend of his, and their messages showed up in my iPhone's messages. Now EVERYTIME he uses it for FaceTime and messages it shows up on my phone.

Ask your cousin to bring the Touch over to your house.

Then, connect the Touch via USB.

Then, in iTunes, under the App Store > Store TAB de-authorize your computer.

Then, and this is important, Google search for:

Return iPod Touch to Factory new condition

And finally, reset the Touch to Factory new condition. And finally, tell him to create his own iTunes Store UserName and Password at home.

TIP: You should have done this stuff yourself, before you gave the Touch to him.