support.apple.com/en-au/TS4515

the activation lock is not really on the ipad it's a theft protection measure on apples servers

it needs to be removed

How to remove Activation Lock - Apple Support

if you don't know your appleID

Recover Your Apple ID - Apple

if that does not help you then you need the assistance of apple

Additional Support - Activation Lock (apple.com)

and or

Get Support (apple.com) ,

And or

 Genius Bar Reservation and Apple Support Options - Apple