From the Landing Pages & Popups dashboard, head to your Popups & Pages List View.
Edit Design or Fields
Click into the form name or select the Edit button next to the form.
Clicking in to any of the wizard headers will allow you to make changes to the form. When you're finished, continue to Publish and then select Finish to save:
Duplicate, Delete or Activate/Deactivate Form
From the form list view, select the drop down in the right column to quickly duplicate the form, delete or activate/deactivate.