As a manager you can view an employee's P45 by following the steps below:
Go to Payroll and then click on Payslip Admin.
Click on Data Files and look for the P45 document type.
Once you find the one required you will have 4 options: View File, View Data, Reload Data and Remove Data.
Choose View File, which will display the P45 files that were uploaded on that batch and look for the required employee.
📌Note: The P45 file data needs to be uploaded via a file import which payroll normally do, if it's not uploaded, please check with your payroll adviser. As a manager, you can find an employee's P45 details from a previous job in their profile.