From what I understand, Bungie accounts always need one other tpye of account linked to them. To unlink an account from a Bungie account, you must have another type of account still linked to it. If I understand, though, you have two different Bungie accounts and each is linked to another type of account (Microsoft and Facebook). If you would like to consolidate those, you'll have to do what EZcompany2ndsqd suggested... Create a fake Google account and link it to the Bungie account that you do not want to keep. Unlink the other (Microsoft or Facebook) account from that Bungie account and link it to the one you want to keep. It sounds complicated because I've used the word "account" about a tousand times, but it's really not.