HI jof
Yes - remove the packages (e.g. rpm -e on RHEL/Centos).
For a typical Linux client you will find these packages installed:
VRTSnbclt
VRTSnbpck
VRTSpddea
VRTSnbcfg
Use the command rpm -e with the 4 packages above and this will remove the client software. You will need to tidy up the /usr/openv directory (i.e. remove it) following the uninstall (if your distro is Debian/Ubuntu, I'm not entirely sure how the client is installed/uninstalled sorry, but this may simply be a "rm -rf /usr/openv").
Finally NetBackup will install VRTSpbx, which may also be used by other Veritas products. It can also be removed if it is not required.
Cheers
David
Update - I just saw the most excellenmt reply from quebek - this answers the question much better than I (although it does ignore that Debian/Ubuntu don't use rpm AFAIK).