disable prepaid option on invoice type drop down

Summary:

I see a declined idea saying this could be done via page customization but I do not see where we can customize the values in the drop down.

Content (please ensure you mask any confidential information):

How do we remove this option? Users do not understand it and select it on accident.

Version (include the version you are using, if applicable):

23D

Code Snippet (add any code snippets that support your topic, if applicable):

NA