Trouble Deleting Exchange Account

I had my work e-mail set up in the Mail app on my personal phone. Our portion of the company was recently sold, and we now have a new domain name. I have deleted the Exchange account and attempted to sign into the new account with my new e-mail address, but it keeps just signing me into my old account. I have tried this several times. I have deleted and reinstalled the Mail app, hoping that it would delete everything associated with it, but that didn't work. I've tried restarting my phone while the app was deleted, but that didn't work either. It just keeps logging me into my old work e-mail. I've tried searching for a profile in my settings, thinking maybe that needs to be deleted, but I haven't been able to find one. I am hoping someone here might have some ideas on what else I can try. Even our IT Department can't figure out why this is happening.