A sign-up form can be disabled or deleted through it's drop down options.
As for the Universal Code, I apologize but this code connects to all forms. At this time the universal code we supply, does not allow the option to specify which Pop Up form form appears. While on the other hand, inline forms can be specified through it's inline code. Are you looking for a specific code to each pop up form you create? If so, this is a feature request we are collecting feedback on so user can have different pop up forms or inline forms for different websites they manage.