You can delete an employee record, but only if you haven't processed a payroll for that employee.
From the Employees tab, select the relevant employee.
From the Employee Details tab, scroll to the bottom of the page.
Select Delete employee.
This option will only work if you've not processed the employee in a pay run yet.
To confirm you want to delete the record, select Delete Employee.
This employee will no longer appear in your employee list or on any payroll reports.