Displays information on the usage if any connected apps in the organization. It also displays View App Info, User Count and Action. In Action you can Click Block to end all current user sessions with the connected app and block all now sessions and Unblock to allow users to log in and access the app at another time. User count shows the number of users who are using the connected app.
Setup > Manage Apps > Connected Apps OAuth Usage > Block (Salesforce Help & Training)
Click User Count > (List of Users) > Revoke or Revoke All to end user access to the current sessions.
Click Unblock Salesforce Help & Training to access the Salesforce Help & Training.