Jumping to conclusions isn't very nice of either of you. If he is trying to hijack a script, I'm sure the script creator would notice. Leave that to them.
Back on topic, there are usually two strings in the gamemode: szGameModeName and szGameModeAuthorName. Edit szGameModeName to change the name of the mode, and/or szGameModeAuthorName to change the script author. However, unless this is used in a command in the script, it doesn't make a difference.
But remember, failing to give an author credit won't get you sued, but you'll probably be hated by most of the VC:MP community.