It's good to see you here in the Community, jpodobni.
I'd be happy to show you on how to make an employee inactive in QuickBooks Online. Here's how:
To give you more of an idea about this process, here's a great resource that you can check: Add, edit, or inactivate an employee.
You may also find below articles helpful in the future:
I'd appreciate if you can update me on how it goes. I'm always here to offer additional assistance. Have a wonderful day ahead.