If you have Active employees who are no longer using the system, you can mark these as Inactive, and they will no longer count towards your employee limit. To do this, highlight the employee in your employee list, and click “Change Status” at the top of the screen. You should now be able to add a new Active employee.
However, if you have reached your employee limit, and all of your employees are still Active, you will need to upgrade your account. You can do this by going to Settings –> Account Settings, and selecting the most suitable plan from the “Change to Plan” drop down menu.