So after talking to customer service for weeks and getting nothing but shady bad answers I will have to try here.

So we bought a pre-owned xbox onx x a few weeks ago and when we downloaded fifa 20 and wanted to sign into the ea account it shows an email none of us knew, we cannot delete it or choose to lock in differently. The one who previously owned it has no idea whose email adress it is. I want to know how to remove this email, however in order to add a number or another email it says I must verify the false email adress and type in a code whcih I cannot do since it is not mine. I am so stuck here please help me, did any one experience this issue before?
I need to remove my gamertag from this false email but I don't know how.