When you first use Team Forms it will request some permissions that are needed for the application to function and store all collected data inside your teams SharePoint. If you no longer require the Team Forms service you can revoke all permissions granted to the app. This can be done by an individual or by an administrator across the entire organisation.
Revoke Permissions - Individuals
Team Forms uses delegated permissions exclusively, this means the application acts on behalf of the signed in user. An individual user can revoke any permissions she granted by following the steps below:
The the app management screen provided by Microsoft My Apps (microsoft.com)
A list of applications that have been granted permissions will appear. Search this list for Team Forms and Team Forms Sharing (note that Team Forms Sharing will only appear if the user has used the public forms feature)
Click the "..." icon next to app and click "Manage your application". This will launch a new screen
Click the "Revoke consent" button
Revoke Permissions - Organisation Wide
As an organization administrator you can also have the ability to revoke permissions for all users across your organization using the steps below:
Navigate to the Azure Portal
Open the Enterprise Applications Resource. Locate and click Team Forms.
Click the properties tab form the side menu
Next delete the enterprise application instance.