How to Add or Remove Capabilities to User Roles in WordPress
you need to visit the Members » Roles page and click on the Edit link below the user role that you want to modify.
This will open the user role editor where you will see different sections in the left column and available capabilities to the right.
You’ll notice two checkboxes to Grant or Deny the permission next to each capability.
If a user role is granted permission that you want to take away, then you need to uncheck the Grant option and check the Deny box.
For instance, if you want to prevent the Author user role from publishing blog posts, then you need to switch to the Posts section and then check the Deny box next to the ‘Publish Post’ option.
Similarly, you can also give additional capabilities to a user role.
For instance, let’s suppose you want to allow users with the Author user role to be able to moderate comments as well. By default, the Author user role does not give users permission to moderate comments.
To do that, you need to switch to the ‘General’ section and check the Grant box next to the Moderate Comments option.
Don’t forget to click on the ‘Update’ button to save your changes after you are done modifying a user role.
You can now create a new user account with that particular user role and log in to make sure that your customized permissions are working as you intended.