As you were told back in February, the cooldown for re-enabling Cross-Save was 90 days. After you disabled Cross-Save, you could have unlinked the account and linked the correct one then. There was no lock out from unlinking the account once Cross-Save was disabled until March 25th. If you had disabled Cross-Save when you originally asked the question about unlinking and the cooldown, there would have been no issues for you to change accounts. I can't find anywhere where someone told you there was a cooldown for unlinking the accounts, only for re-enabling Cross-Save. Unfortunately, as of March 25th, you can no longer unlink accounts. By choosing to wait instead of unlinking it before, you've locked yourself into the accounts as-is. Your only workaround for this is to link the account you want to use to a new Bungie.net profile and set up a new platform account to use it with Cross-Save on that platform, but this means you'll be using new save data. There's no other options available.