Log on to Veeam Extensions Server (VES) and run regedit. Locate the following key:
HKEY_LOCAL_MACHINE\SOFTWARE\Veeam\Veeam Virtualization Extensions for VMware\Manager
and set the value ResourcePool to a blank value. This will trigger uninstallation of all collectors, which can take up to 8 hours depending on the size of your infrastructure. To speed it up, you can restart HealthService on the VES Server.