In your post, you said 21 days to unlink since you purchased Silver. You already have your Steam connected to your Bungie.net profile and set up with Cross-Save, if that's the right Steam account, then you don't need to disable Cross-Save. If you want to access your characters, you just need to log in with Steam using that same account. If you want to link a new Steam account instead of the one you have now, then you'll need to wait for the Silver time to finish, and then you'll have to disable Cross-Save. That will lead to another 90-day wait before you can re-enable Cross-Save. While Cross-Save is disabled, each of your accounts will go back to its own save data.