I don’t need any of the pay features, what is the best way to achieve this? Can I just cut it down to one signup form, since only admins will be adding, deleting, editing listings?
Yes, login as an admin and navigate to the the signup page and click the "Settings" button as follows:
Check the "Hide" checkbox next to the paid listings as follows:
Scroll to the bottom of the page and click "Save" settings and you now have a free listing signup!