How do I bypass the limit on a singer baseboard heater?

You do not do that. The limit is a safety device and should never be bypassed.

I had found on another DIY site( I think king electric) and it said if I was getting juice ate the heater to bypass the limit and that would tell me if the heater was working or not.

You test the limit control with a meter. Now if you want to temporary jump it that is up to you. First you have to find the limit and it will be somewhere along the voltage path. Without being there I do not know exactly where it is at.