My modems are not in the Model drop-down list. Mine are both: Archer A7 v5.0 firmware version 1.0.15 build 20200721 rel 40773.

I am a bit confused here. I have 2 identical AC1750 Dual-Band wifi routers. I have just had to restore-to-factory settings on one of them and am in the process of bringing it back to working order. During the setup phase, I entered an email address that I had used before but got the message that I could not use it because it was a "registered" address. How do I "unregister" the email addresses? I do not know just how many registered ones in my accounts. I want to unregister all of them - on both AC1750s and start completely over if I have to. Suggestions?