Someone has there apply I’d connected to the AirPods max i just bought(used) how to i disconnect them

From:

How to reset your AirPods Max - Apple Support

AirPods Max can be associated with one Apple ID. If you want to use AirPods Max that someone else has used, they need to first remove them from their Apple ID.

So contact the seller. As long as the seller did not sell you a stolen product he should be able to remove them from his account