To delete the user you need to have Admin’s permissions.
Navigate to Settings (1) and Users tab (2).
You can remove the user by clicking the trash can on the user’s section:
or check the name of the users, click the bulk edit button and delete them:
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.