OK, I did this for my forum today.
I altered it so only superadmin can physical delete in the front-end.
search for: $show['harddelete']
posting.php
PHP Code:
//hack start
//$show['harddelete'] = iif(can_moderate($threadinfo['forumid'], 'canremoveposts'), true, false);
$show['harddelete'] = iif(in_array($bbuserinfo['userid'], preg_split('#\s*,\s*#s', $superadministrators, -1, PREG_SPLIT_NO_EMPTY)), true, false);
//hack end
search for: $show['physicaldeleteoption']
editpost.php
PHP Code:
//hack start
//$show['physicaldeleteoption'] = iif (can_moderate($threadinfo['forumid'], 'canremoveposts'), true, false);
$show['physicaldeleteoption'] = iif(in_array($bbuserinfo['userid'], preg_split('#\s*,\s*#s', $superadministrators, -1, PREG_SPLIT_NO_EMPTY)), true, false);
//hack end
hope this could help you.