It should be of no surprise to find left over keys from security related software in the "Enum\Root" areas of the registry, and do note there's more than one area they're stored in.
Typically left over keys in that area will have to have Admin rights placed on them so they can be removed, instructions:
Registry Permissions:
It's also common with many security applications ("antivirus, firewall, etc.,") which may create entries in a particular area of the registry that even an Administrator account can't remove unless the permissions are changed to full access. Still in some instances changing the permissions won't allow you to remove the registry key(s).
Warning:
Manually editing the Windows registry is extremely dangerous if you don't know exactly what you're doing, any mishaps can result into the re-installation of software, or worse Windows itself. Even if you know what you're doing you should create a backup of the registry before manually editing it. Users of Microsoft Windows NT, 2000, XP, 2003, and Vista can use ERUNT (100% clean freeware, no adware, no spyware) to make a known good registry backup. Note: If you're not comfortable editing the Windows registry then don't do it, better safe than sorry!
ERUNT is available here.
How to manually set registry key permissions to Administrators:
1. Make a registry backup first either with ERUNT, or System Restore.
2. Click Start, Run, and type in: RegEdit
3. In RegEdit navigate to the key.
4. Right click the registry key to display a pop-up, then click: Permissions
5. Now click: Add
6. Input into the field named 'Enter object names to select': Administrators
7. You "should" now be able to successfully remove the key.