How do I remove a fieldset for a dexterity content type?

Hello, I am not very familiar with plone and was wondering how I can remove a fieldset for a dexterity content type? I am also wondering how I can move fields from one fieldset to another. For some reason when I try to add a new field with a fieldset seelcted, plone still adds the new field to the "Default" fieldset. Thanks in advance for you help with what is probably a simple question.

My sample code is at https://github.com/l34marr/crgis.content/blob/master/crgis/content/interfaces.py#L169 Hope that helpful.

I'm sorry but I don't really understand the meaning of your sample code and how that helps me.