It may be that you have Forms stored in your Active folder as well as in your Archive folder. Archived Forms will count against your total Form allowance set by the Form Plan. If this is the case, you will either need to unarchive and use these Forms, delete them to create room for more Forms or upgrade to the next Plan level.
To unarchive (reactivate) a Form , go to the Forms menu > 'Archived Forms' folder menu > Place a check mark to the left of the Form(s) > Click the Restore option along the top of the page.
If you would prefer to delete a Form, go into the Forms (or Archive) menu > place a check mark to the left of the Form > click the delete option.
If you are wanting more forms, you can go to My Account > Billing > Form Plans to check upgrade to a higher plan.