Want to unlink an unknown ea account from my steam account

I just purchased fc 25 through steam . And while I tried to link my EA account to my steam , it says my steam is already linked to an account and I have no idea what that account is . I know it’s not mine . Somehow it’s linked to my steam account . So u want to unlink that ea account and link mine so u could play online in fc 25 . Pls help