As I saw I couldn't enter the Underforge since I was now a vampire, I waited a while so I could get the "Your follower leaves your service..." message. But I didn't. So I just did some of the quests for the DLC.
It's been a week in-game and I still have Aela as a follower, and can't talk to her since she's locked away in the Underforge.
So I decide to load a save I did seconds before choosing what side I'd pick for the DLC (Dawnguard or Volkihar) and went with Dawnguard, and got teleported out of the castle. So I check my Miscellaneous quests to find the "Talk with companion leaders for work" and try to find Aela.
Aela is now inside the castle I just locked out of.
Is there any way I can get rid of followers without interacting with them?
Please answer this, for I am desperate.