Old Acc. Banned, Disconnect from Xbox?

Hi, I used to have an account on Overwatch called Gengu#something, and it was linked to my Xbox account. That Overwatch account was banned, and now I can’t use the Overwatch account on Xbox either. I was just wondering, if I could disconnect that battle.net account (somehow, I don’t have that account anymore), would my Xbox Overwatch account remain suspended indefinitely? If I could disconnect my Xbox Overwatch profile to unban it, would I need to log in to the battle.net account or is there any other possible way? Thank you…