back up page for webinars

Hi All, 

I am pretty new to Marketo and I have been tasked with setting up a webinar. I use WebEx as our event partner. I did all the set up and forgot to update the "back up page". When I try to update the system gives me an alert that I cannot edit once the program has members in it. I and a few of my colleagues signed up just to test it, we are the members. Can anyone provide a workaround? 

Thank you,