Remove MacBook from Apple ID, is extended warranty still valid after that? I want to sell my old Retina MacBook.

I know how to erase/reinstall the Retina MackBook, but two more questions remain:


How can I unregister it from my Apple ID?
Is the extended Apple Care Warranty still valid after that?
Just logout (and install it from scratch after format) or check this Kb
Apple Care is bought for a device, so yes.