// Gitlab Omnibus

~ sudo -u mattermost -i bash    
$ cd /opt/gitlab/embedded/service/mattermost
$ /opt/gitlab/embedded/bin/mattermost  -config='/var/opt/gitlab/mattermost/config.json' ...

// delete team
$ sudo -u mattermost -i bash
// save dtb
$ /opt/gitlab/embedded/bin/pg_dump -U gitlab_mattermost -h /var/opt/gitlab/postgresql -p 5432 mattermost_production > mattermost_production_backup
$ sudo -u mattermost /opt/gitlab/embedded/bin/mattermost -config=/var/opt/gitlab/mattermost/config.json -permanent_delete_team -team_name=""