Managing your users is super simple! Go to Settings > Users
Here, you'll see 3 main options:
Edit Roles - allows you to create and define roles for the account, each with their own sets of restrictions and permissions
Delete - allows you to delete a selected reader for user-management
Create - allows you to create, or essentially, add a new user to the account
To delete an actual user, select the box adjacent to their name and hit 'Delete.' A window will pop-up to prompt you one lat minute. If you're good to go and intentionally want to delete the user, select Confirm.