Before you sell, give away, or trade in your iPad, see the Apple Support article > General > Transfer or Reset iPad > Get Started, then follow the onscreen instructions.
Sign out of iCloud and the iTunes & App Store. Go to Settings > [your name], scroll down, tap Sign Out, enter your Apple Account password, then tap Turn Off.
turned on Find My for your iPad, Activation Lock is removed when you erase iPad, making it ready for a new owner.