Please follow the below procedure to process a Leaver and generate the Form P45:
1. Input the leaving date of the employee under employee details, refer attached.
2. Run and submit the payroll to HMRC to update them. It is necessary to run at least a single payroll to notify the Leaver to HMRC and generate the Form P45.
3. Once done you may download the P45 by following the below link:
Reports>>Additional Forms>> P45
Please refer below screenshot for more help.