Fulcrum gives you granular control over which users in your account have access to each app. The ability to manage what users can access what apps can be done from two locations, the app's dashboard page and the members permission page. The best option to use will depend on your use case. If you wish to grant/revoke a specific user access to multiple apps then it is probably best to use the members permission page. If you wish to grant/revoke a group of users access to a specific app, then it is probably best to use the app's dashboard page.
You can see how to leverage the members permission page here.
Granting/revoking access through the app's dashboard page.
From the homepage of the Fulcrum web app, select the name of the app that you wish to grant or revoke access to. This will take you to the app's dashboard page. Once you are on the app's dashboard page:
Select the Member Permission button to see a list of all users that currently have access to your app.
When the Member Permission modal is displayed search or filter users to move users from the left panel (Available Members) to the right panel (Selected Members).
To revoke access to the app, move user from the right panel to the left panel.