"Windows couldn't remove your computer from the homegroup."

I ran the homegroup troubleshooter for the same problem. It reported that windows firewall was not configured to allow the homegroup service and offered to automatically fix it. Once done I was able to leave the homegroup. I had homegroup services running during the troubleshooting. Hope this helps.

It is likely that in seeking a resolution some of the "fixes" have cascaded into a series of other little problems. Any one of the steps mentioned, if modified incorrectly or not solved in a specific order will make the issue harder to solve, or worse.  :(

If a reinstallation of windows becomes the only way of fixing it, I might recommend using Windows Easy Transfer to migrate your documents, music, email settings, etc... by saving the transfer file(s) to disk, then open the transfer file after reinstalling Windows.

Refrences::

Below nljackson65's response and

http://social.answers.microsoft.com/Forums/en-US/w7network/thread/647907b2-5ba6-4fc5-b724-266bdfaddd37/

Geek Squad Double Agent

Here is a solution that might work.  It worked for me. 

"Researched the problem and found the solution. A file was corrupted and deleting it got the PNRP service running. The file was recreated correctly when the PNRP service started up. Here's the file for future reference:

C:\Windows\ServiceProfiles\LocalService\AppData\Roaming\PeerNetworking\idstore.sst"

Solution given by Streetwolf on Windows 7 Forums

Link is below:

http://www.sevenforums.com/network-sharing/29060-cant-start-peer-name-resolution-protocol.html

 

 

This worked like a charm!! Thanks for the tip!

I had a similar issue just recently and none of the fixes mentioned anywhere worked.

First thing was to figure out exactly what clicking "Leave the homegroup" does. I opened Process Monitor, added a filter to include results from explorer.exe (as that's the process that spawns the control panel window) then started capturing. Clicking on that link caused explorer.exe to create a new thread then destroy the thread with nothing in between, so I disabled the filters and saw that it was calling svchost.exe. svchost.exe then traversed the registry until it hit a snag. One registry key was giving an access denied error.

HKEY_CLASSES_ROOT\CLSID{C90250F3-4D7D-4991-9B69-A5C5BC1C2AE6}

Instead of fiddling with permissions, I exported that key, deleted it, then re-added it, and lo and behold, no more access denied error. After this, I did the usual routine of stopping the three Peer* services, deleting the C:\Windows\ServiceProfiles\LocalService\AppData\Roaming\PeerNetworking folder, then restarting said processes. This time, clicking on Leave the homegroup worked as intended. With a few more tweaks (disabling and stopping the two HomeGroup services), any mention of HomeGroup in the navigation pane in Explorer was gone.

Ironically, starting the HomeGroup Listener service still gave me some about %%-2147023143. But nevertheless, I'd fixed my issue so all was well.

When in doubt, bust out Process Monitor.