Very similar to cleaning up Sumo Subscriptions and Product Feed Pro you might be having some issues with removing everything from WPForms (an excellent plugin that I highly recommend).

This likely happened because your friend was using a cracked version of WPForms Pro and now you've they've decided it's such a good plugin with so many cool integrations that they want to buy the full version.

So you they buy the full version only to find that all of the main settings are still inactive.. because of the cracked version they previously had. So now you need to do some cleanup, but where to start?

1. BACKUP: Backup all of your forms and export your entries. You'll need these in a little bit.
2. UNINSTALL: Uninstall the WPForms Pro plugin. If you put a legit license key you can also remove/deactivate.
3. INSTALL Foxco's WPForms Cleanup Tool here. Run the plugin and remove all traces of WP Forms
4. UNINSTALL Remove the Foxco plugin, you won't need it anymore.
5. INSTALL & ACTIVATE: find your legit WPForms plugin, license key and backup files and install all of them, now clean as a whistle.