Registration rejected because I'm already there

I recently successfully added a Ring Doorbell. I also added Smoke Alarm listeners but couldn't get them to connect to my WiFi. Guessed that my five-year-old base station probably needed an Ethernet connection to my Comcast modem. I got to the end of setting this up but got a message that my email (I think) was already used. I guess that's from setting up my doorbell camera or maybe from 5 years ago when my kid set this up. I realize now that the door contact sensors may never have been connected to anything because they always read "off-line." How do I get the system to accept that I am the same person and "merge" these two accounts. The message says that you can't have more than one account per location. Will I have to undo something? Can someone please help?