Can VGP be removed if I am not using it on 4.x ?
Yes, you can do the operating system package removal command and remove it.
HP - swremove vasgp
Solaris - pkgrm vasgp
AIX - installp -u vasgp
Linux - rpm -e vasgp
VGP extends Microsoft Group Policy functionality to Unix and Mac environments. You can use policies to do alot of things but here is a few example. Some customer like to set their vas.conf settings in it. Once a system joins it does a vgptool apply which brings the settings down to the machine so they are set automatically at join time. Another example is users.allow file settings are applied at join time.