Each user must give their express permission to allow an application to access their NetDocuments account. This is done when logging into a given app for the first time. A user can revoke these permissions at any time.
To access this page, go to Settings > Manage Apps. This list includes all NetDocuments-supplied client software, as well as third-party apps built with the REST API that you have authorized for use via the OAuth flow. This might include ndOffice, ndMail, Workshare, etc.
Clicking the Revoke Access link will remove all access to that app from your NetDocuments account.
Learn more about Logging out of Apps.