Ya I used the account that I made at my friends house on my PS3, Im thinking that if I delete my User it will work but im not sure

Heres the problem, before Christmas I made a PSN account at my friends house to get some trophies, Then I got a PS3 but noticed that I'm not the Master Account and yes im the only account on my PS3, also I am unable to buy stuff from the PSN store or even add funds, so how could I fix this?