Is it a feature or bug that webmasters can not be removed?
If it's a feature, it should be prompted when trying to remove a webmaster.

What I am doing: set a super webmaster, for say the Administrator created during installation. Only this webmaster has the permission to remove other webmasters. This super webmaster can not be removed or terminated.

onokazu wrote:
This actually was a new bug found in 2.0.6, and I have just committed a fix on CVS.

Add the following line to /modules/system/admin/users/main.php, just after line 93

$deluser =& $member_handler->getUser($memberslist_id[$i]);

so it will look like below:

$deluser =& $member_handler->getUser($memberslist_id[$i]);
$groups = $deluser->getGroups();

We will be making the release of 2.0.6.1 or 2.0.7 very soon which includes this fix.