To fix a corrupt quorum:

 net start clussvc /FIXQUORUM

The Cluster Service service is starting..............

The Cluster Service service was started successfully.

If you cannot start the Cluster service, or if you have trouble removing the node, you can manually unconfigure the Cluster service:
1. Run the Cmd.exe program to open a command prompt.

2. At the command prompt, type

 cluster node nodename /forcecleanup 

then press ENTER

Note: If the Cluster service does not exist in the registry, the command does not respond. To create a place holder, type the following line at the command line, and then press ENTER:

  sc create clussvc