If I rehire and old employee should I edit old employee or re-enter ?

Hello there,@todd22.

You can filter your employees' list to Inactive employees. From there, it'll show the employees you've marked as inactive. Let me guide you how.

1. From the left panel, click Workers.
2. Select the Employees tab.
3. From the Employees list section, select Inactive employees from the drop-down menu.
4. Double click the employee name you've terminated or mark as inactive.
5. Click Edit employee besides the employee profile.
6. Select the Pay tab and edit the employee info and click Done.
7. Go to the Employment tab and select Activate from the Status drop-down menu. 
8. Click Done.

I've got you these great articles for additional reference:

• Delete or terminate an employee
• Add, edit, or inactivate an employee

Also, here's an article you can check in case you want to run your payroll in Quickbooks Online.

If you need anything moving forward, we're just a post away.