If you really want to have a delete button there it is only possible with some strange hacks 
Define a “Custom action” with a link like this
javascript:(function(){document.body.innerHTML='<form method="POST" action="http://<my_mon_server>/<instance>/check_mk/webapi.py?action=delete_host&_username=automation&_secret=<automation_secret>"><input name="hostname" value="$HOSTNAME$"/></form>';document.forms[0].submit()})();
Then you can assign this action for the hosts as “custom icon and action”.
But i would strongly recommend also the way @r.sander has described.