MEE6 cannot give/remove roles or kick and ban bad people when his role is too low in the hierarchy.
There's a simple solution to that, here's the recipe.
Check that MEE6 role is high enough in the hierarchy
Go to your Discord server settings then click on Roles. Then, click on MEE6's role and move MEE6's role above the other roles.
If MEE6 is still showing you the error message, please join our support server. We'll be happy to help.
Updated on: 24 / 06 / 2019