To delete a form, the collection that was created for it must be deleted. To do this, click on the name of the open form and select the collection in the form settings. 

This opens the collection settings, from which you can further personalize and customize the form. Scroll all the way down to find the option to archive or permanently delete the form.

Confirm the deletion/archiving process in the window that appears. 

Please note, that this action can not be undone.

Click here, to learn more about the archive!