Hey there, in addition to the answers given, Steam is your primary account, it is the Active account in cross-save and it where your characters originate from. Any time you may have played on PSN or Epic, you were logging into and playing your Steam characters. To want to unlink Steam would mean to abandon the existing characters, all progress, inventory, etc. So really, you need to recover the account, not try to abandon it, as doing that would mean starting over from nothing. Bungie will never forcibly unlink accounts under any circumstances.