i have a ipad with remote management lock i bought and didnt know it was on the device

I’ll assume this is Activation Lock, not remote management. This iPhone is effectively lost or stolen, and only the original purchaser with the purchase receipt and matching ID and a visit to Apple, or the user holding the password to the Apple ID account holding the lock, can release the theft-deterrent Activation Lock.

If you don’t have the password to the matching Apple ID, and if the seller is no longer available to accept a return or refund or to remediate this, turn that iPhone into the police. Or back into the company holding the lock.

The All Too Common SAD Reality of Buying a used iPad/iPhone - Apple Community

You won't be able to. Only the company that placed that lock on there can do it.

~Lyssa