You must let the server create a new world each time you delete a plugin. Even if you remove the plugin that is causing the problem, it has...
I Of the ones you have listed, I am using Essentials, Group Manager, Essentials Spawn, WorldEdit, and WorldGuard and it is working for me so it...
It is a plugin. You will have to delete the world each time because even if you delete the plugin that is causing the problem, the world has...
Separate names with a comma.