icloud activation problem

I have ipad 2 the prob is my. Icloud account i.have apple. Id before that has been link to. My ipad. I already forget the email and passwd because that was very long time account even the security question. I forgot possible to delete and sign out by apple support. This the serial number of my ipad 2 DVPH7MXZDFHW 16 gigabyte iOS 9.3.5 i cannot activate my ipad because of that i cloud activation