If you log into the "Service Catalog" application in EEM UI as eiamadmin, go to "Manage Access Policies" and then click on "Launchpad", you can see the way that the interface is built for a role.
If you look at the "ACL_113_Launchpads" ACL (end user role), you can see this list:
"launchpad__my_dashboards" listed above is why the "End User" role can see the dashboard tab when the users with "End User" role login catalog UI . If you want to remove the dashboard tab for "End User" role , you can simply remove launchpad__my_dashboards from ACL_113_Launchpads . then , recycle EEM services and catalog service .