Merge pull request #7422 from bbodenmiller/rm-gitlab-user

Add command to remove GitLab user

doc/update/4.2-to-5.0.md

@@ -163,3 +163,7 @@ sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production
 ```
 
 **P.S. If everything works as expected you can remove gitlab user from system**
+
+```bash
+sudo userdel -r gitlab
+```