Sometimes you might end up waiting for more than 30 minutes or more to stop the DHCP server on Windows 2008 onwards. Sometimes waiting for much longer. Well to manually kill the process you will need to first find the PID of the process DHCP server and then kill it.
Make sure you run the command line ‘As Administrator’
sc queryex dhcpserver
this will give you the information on the DHCP server process including the PID number. Keep note of this and then run:
Taskskill /F /pid (PID number)