Today I came across an issue with SCCM that I have never had to deal with. One of our AD controllers at a remote site took a dive, this system was also our site system for this location. I was able to remove the Distribution Point and Software Update Point Roles from the server but when I tried to delete the Component Server Role I had a greyed out remove. Trying to delete the whole system returned an error:

If you would delete the system from AD and wait 24 hours the clean up process would detect the change and allow you to delete it the next day. This wasnt good enough because I needed a quick turn around. To get around this timer, head into the registry: HKLM\Software\Microsoft\SMS\Components\SMS_SITE_COMPONENT_MANAGER\Component Servers\SERVERNAME
In each subkey but also including the root, there will be a key called “Deinstallation Start Time”, set this value to 1.

Once this is done for each subkey, restart the Site Component Manager Service. At this point you should be able to delete your failed Site Server from SCCM!