To delete the user you need to have Admin’s permissions.
IMPORTANT: Remember that deleting users will not change the number of available licenses in your active subscription and will not reduce your monthly charges. If you wish to downgrade a number of your licenses, you need to adjust your subscription through the Subscription tab.
Navigate to the Users tab.
You can remove the user by clicking the bin icon next to the user’s name:
You can also delete many users at once. Just check the name of the users, click the Bulk edit button and delete them: