Removed Deck app but icon still persists in header

We are piloting Nextcloud 16.0.1 and I loaded the Deck app and our team decided against using it. I disabled the app and then removed it, but the icon in the header still shows. If I select it I receive the following message:

Service Unavailable

The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.

Additionally, a 503 Service Unavailable error was encountered while trying to use an ErrorDocument to handle the request.

As I am a Newbie, I am assuming that I did something incorrectly when trying to uninstall the app. We are getting new groups involved and would like to not have the icon persisting.