Help!

Does anyone know if I have to let CSULB know if I don’t plan on attending for the Fall’15? When I had to accept my offer back in June I accepted SFSU and CSULB because I wasn’t sure which school I wanted to go to due to personal reasons. I have gone through with orientation at SFSU and have already registered for classes so I’m positive that I will go to school there in the Fall’15. I tried looking for the admission’s email so I can let them know, but I haven’t been able to find it. If anyone can give me the email I would appreciate it.