Removing a contributor
If a contributor doesn't need access to your site or if they leave your organization, you might want to remove their contributor profile. This blocks them from logging in and making any changes.
When you remove a contributor, you'll transfer ownership of their content to a different contributor.
If someone may need access later (like a designer who built your site), you can remove their permissions instead.
Step 1 - Click on Settings then Edit Users
From the dashboard click on the Settings Link in the left sidebar. Hover over the User section and click Edit.
Step 2 - Check the user you want to edit
You can remove a user or change the permissions of the user. After selecting the check box you can remove the user from your account by selecting the "Bulk Actions" dropdown and selecting Remove and clicking the APPLY button. Or you can change the users role by selecting the "Change role to..." dropdown and choosing a user role and clicking the CHANGE button.