Thanks for your reply. I tried three different numbers without any success, despite hanging on for over an hour in total.
I have recently taken out paid RAC Breakdown cover as the AA were too expensive, I bought a car a year ago which came with free RAC cover, which they generously renewed free for another year, hence two accounts. I also have a third account as a couple of years ago another car I bought also had a free years cover. I now have three membership numbers, but I can’t do anything as the original MYRAC account is set up with my email. Consequently I cannot delete or activate the surplus accounts.