I logged onto my bungie.net account and noticed that there was a PSN account linked to my bungie.net profile that I do not recognize. It isn't my PSN account and I am unable to unlink it since this requires me to authenticate it as my account by using it's login information, which I don't have because it isn't my account. I have no idea how this PSN account was linked but I know that I didn't link it and that it isn't mine. Is there was a way for this PSN account to be unlinked from my bungie account?
Unfortunately you are the only person who can unlink an account from your profile. You will need to know the credentials and be able to log in to it to do so. If you are having trouble, you may want to reach out to PlayStation customer support to see if they can help you recover the credentials so you can unlink it.