The Persistent Sessions panel lets you disable the option for users to stay logged into Looker:
By default, when a user logs into Looker, they are given an option to stay logged in:
When a user selects the option to stay logged in, they will be authorized to access Looker for 30 days. When they close and reopen their browser, they can navigate to Looker without being required to log in again.
Disabling Persistent Sessions removes the “Stay logged in” option from the login screen. Users will be automatically logged out after 30 minutes, or whenever they close their browser. This forces users to re-authenticate the next time they access Looker.