Can I disable the /help command in this plugin? If so, how?

Read the title

what version do you have? I had an idea, and tested it - maybe one of my plugins was overriding it but I ran this plugin only and it still said unknown command.

if you are running the newest version, this is just a stab, but goto line 220 find this and delete it

private void SendHelpText(BasePlayer player) => SendMessage(player, HelpText);

You would be using a plugin such as HelpText for that to be used. This plugin doesn't do anything with that natively.