Hi Zismo, if you go into the config of the plugin and Control+F (or just scroll down) "Lightning," you will find something that looks like this:
Lightning:
Enabled: true
Description: Hold sneak while selecting this ability to charge up a lightning strike. Once charged, release sneak to discharge the lightning to the targeted location.
You're going to want to changed the enabled setting to false, as so:
Lightning:
Enabled: false
Description: Hold sneak while selecting this ability to charge up a lightning strike. Once charged, release sneak to discharge the lightning to the targeted location.
I hope this helps.