If the case is closed but you still see a case follower room under your messages in the "rooms module", or you still see a case under the "cases module" then it is likely that your filters are set to show closed rooms or cases.
To change this, from the rooms module, you can select the filter icon in the top right of the screen, and select "Hide Closed Cases."
Or from the cases module, you can select the filter icon in the top right of the screen, and select "Open Cases."
This will ensure that all closed or archived cases or rooms are not showing up on your main rooms or cases page.
Note: After resetting the filters, you may need to refresh the app by pulling/sliding down on the main messages and case pages until you see a refresh symbol, or by logging in/out of the app, or by resetting the application by going to more > settings > reset application