As of March 25 2025 you cannot unlink platform accounts (except Twitch) from a Bungie.net profile. The Steam account became permanently bound to your Bungie account once the change was implemented on the above date - you can read about it [url=https://help.bungie.net/hc/en-us/articles/35597981889300-Notice-Bungie-net-Account-Unlinking-Update-on-March-25-2025]here[/url]. This change also means you cannot move a platform account between Bungie.net profiles, so your PSN is also permanently bound to the profile its already linked to and cannot be moved to another Bungie profile either. Bungie will not unlink it on your behalf, so if you want to play on Steam with your characters you'll need to use the already linked account.