IF and only IF you have no other Panda software that you want to keep set a restore point - assuming Win XP - then do a search for any files and folders containing entries for Panda and try to delete all you find.
Go to Start -> Run and enter regedit in the box -> click OK (to enter the registry editor), -> Ctrl+F (to start search) and enter Panda in the box then press [enter].
Check each revealed entry and if it is unambiguous press [delete]. Then press Ctrl+F to continue the search.
If in doubt don't delete.
If you have a registry cleaner like RegScrubXP run that to find any loose bits left behind and "fix" them.
Then do a Restart.
Now that's what I WOULD DO, (and did to get rid of NAV) but others - more expert - may advocate other line of attack.