VMware ESX 4.0 and vCenter Server 4.0 Edition

vSphere Upgrade Guide : About Host Updates and Patches : About the vihostupdate Command-Line Utility : Uninstall a Bundle from a Host

Uninstall a Bundle from a Host
Use this procedure to uninstall bulletins that are third-party or VMware extensions.
Do not remove bulletins that are VMware patches or updates.
Before you can uninstall an update or patch from an ESX/ESXi host from the command line, you must have access to a machine on which you can run the VMware vSphere Command-Line Interface (vSphere CLI). You can install the vSphere CLI on your Microsoft Windows or Linux system or import the VMware vSphere Management Assistant (vMA) virtual appliance onto your ESX/ESXi host. For information about deploying or installing the vSphere CLI, see the VMware vSphere Command-Line Interface Installation and Reference Guide.
Determine which bulletins are installed on your ESX/ESXi host.
vihostupdate.pl --server <server> --query
Note the bundle ID for the bundle to uninstall.
Run the vihostupdate command.
vihostupdate --server <server> --remove --bulletin <bulletin ID>
vihostupdate can remove only one bulletin at a time.