By default, everyone in the workspace can use every app the Owner has connected. The Apps Connections → Admin tab tab lets you enable or disable apps team members can connect.
To restrict access for a member:
Go to Settings → 'Manage' on Workspace row → People & Access tab
Click the member's row to open their drawer
Under Member's own apps, find the app you want to restrict
Toggle it off
When you restrict someone's access to an app, their token for that app is revoked immediately and any automations that depend on it are paused. The member receives a neutral notification that the app was disconnected from their workspace.
To restore access, toggle it back on. Their automations resume.