Setup for Document Type LOV in the Autocreate Documents form

Hello everyone,

In Purchasing module, there are some PO document types that we are not using. Since there is no setup to end-date or disable PO document types, we are thinking of workarounds without doing personalizations.

One of them is: in the Autocreate Documents form, we would like to rename some values in the LOV for Document Type to "DO NOT USE - xxx" (see attached picture for illustration)

So my question is : can anyone tell me where would this LOV be configured ?

For instance, it seems like the LOV for Grouping is a lookup. So I though maybe it would be the same for the Document Type but I couldn't find it.