VIOM has a utility to perform this operation , The utility is called /opt/VRTSsfmh/bin/vomadm  . Below is an example of host removal operation.

# > /opt/VRTSsfmh/bin/vomadm host-mgmt --remove --host rdgv240sol11.mydomain.com

Removing host rdgv240sol11.mydomain.com...
Removed host rdgv240sol11.mydomain.com successfully
Refer /var/opt/VRTSsfmh/logs/vomadm.log for details

 # >  /opt/VRTSsfmh/bin/vomadm host-mgmt --list
HOSTNAME                      IPADDRESS    HOSTID                                 STATUS OSNAME CPUTYPE
----------------------------- ------------ -------------------------------------- ------ ------ -------
tipusol10.mydomain.com   127.0.0.1    {00020003-bad9-9181-0000-000083d99181} UP     SunOS  sparc
rdgt2000-07.mydomain.com 10.12.xxx.xx {00020014-4faa-60f4-0000-000084aa60f4} UP     SunOS  sparc