How can I add notes/reasons for terminating an employee? Or is there a way I can make other options in the Status drop down?

Thank you for posting in the Community, @AMoon.

You can add notes for your Employee in QuickBooks Online. I'll be happy to guide you with the steps.

1. Go to Workers from the left menu, then select Employees.
2. Choose your employee.
3. Click the pencil icon beside Profile.
4. Enter the information in the Notes field.
5. Hit Save.

 Also, you can make other options in the Status dropdown. Just follow these steps: 

1. Go to Workers then select Employees.
2. Choose your employee from the pencil icon beside Employment.
3. Click the Status drop-down then make your changes.
4. Hit Save.

For further guidance, you can check out this article: Add and use notes.

Fill me in if you need anything else. I'll be more than happy to help you. Take good care!