Thanks for your post and welcome back!
I understand you're looking to remove an old account from your BTID. Have you tried calling the helpdesk on 0330 1234 150? We are light on the ground currently and it would take us a few days to get round to picking up your case. My colleagues in the helpdesk should be able to action this to get it done for you today.
Feel free to post back and let me know how you get on chatting with them.