Pontiac Bonneville 1998

Hi peeps, need to know is there anyone out there that knows how to Disarm Secuity System, so I can get my moms car running, the car starts sometimes but my mom at 78 years old has a problem with the secuity light on the dashboard going on and the car won't start, she is always calling me to come get her, HELP. I've tried everthing and seems no one knows how to disarm this secuity system. Some one please help and send me Information, Thanks poemc!