If you accidentally add an employee to BrightPay, you can delete them by navigating to the Employees tab, selecting the employee, clicking 'more' (represented by a blue spanner), and choosing 'Delete.' 

Please note, this procedure can only be performed once no payroll has been completed for this employee. If payroll has been processed and a RTI sent to HMRC, you will have to mark this employee as a leaver.