KMS Server

To remove KMS from a server you need to reset the license key back to the default, this is achieved by running the following command;

cscript c:\windows\system32\slmgr.vbs –upk
cscript c:\windows\system32\slmgr.vbs /ipk <license key goes here>

The license key is taken from the table below;
Table 2: KMS Client Setup Keys

Operating System Edition	Product Key
Windows Vista Business	YFKBB-PQJJV-G996G-VWGXY-2V3X8
Windows Vista Business N	HMBQG-8H2RH-C77VX-27R82-VMQBT
Windows Vista Enterprise	VKK3X-68KWM-X2YGT-QR4M6-4BWMV
Windows Vista Enterprise N	VTC42-BM838-43QHV-84HX6-XJXKV
Windows Server 2008 Datacenter	7M67G-PC374-GR742-YH8V4-TCBY3
Windows Server 2008 Datacenter without Hyper-V	22XQ2-VRXRG-P8D42-K34TD-G3QQC
Windows Server 2008 for Itanium-Based Systems	4DWFP-JF3DJ-B7DTH-78FJB-PDRHK
Windows Server 2008 Enterprise	YQGMW-MPWTJ-34KDK-48M3W-X4Q6V
Windows Server 2008 Enterprise without Hyper-V	39BXF-X8Q23-P2WWT-38T2F-G3FPG
Windows Server 2008 Standard	TM24T-X9RMF-VWXK6-X8JC9-BFGM2
Windows Server 2008 Standard without Hyper-V	W7VD6-7JFBR-RX26B-YKQ3Y-6FFFJ
Windows Web Server 2008	WYR28-R7TFJ-3X2YQ-YCY4H-M249D

So to reset the license key for a Vista client you would run this command;

cscript c:\windows\system32\slmgr.vbs /ipk YFKBB-PQJJV-G996G-VWGXY-2V3X8
cscript c:\windows\system32\slmgr.vbs -ato 

While we wait for the incorrect KMS servers to be removed from the domain, you can manually direct the Vista client you are having trouble with to a specific server running KMS by running this command;

cscript c:\windows\system32\slmgr.vbs –skms myserver.domain.com

For further information review the Deployment Guide