Deleting employees is not a feature at this time, as it would delete any historical data associated with that employee (jobs, estimates, records of clocking in and out, etc).
However, sometimes employees part ways, and you need a way to remove access to Service Fusion. You can make the employee inactive by going to My Office > Workforce Management, finding the employee you wish to make inactive, clicking the pencil icon at the end of their row to edit, and then click the Access tab.
Flip the toggle switch labeled "User Account Status" from Active to Inactive. This will remove them from the Dispatch Grid, remove the ability to assign them to a task, estimate, or job, and will prevent them from being able to login.
Be sure to use the green Save button, to save any changes made.
If your employee returns to your employment, you can always make them active again, by simply flipping the switch the other way, from Inactive to Active.