A similar question was asked: how-do-i-disable-an-add-in-in-word
However, I want to know how to disable a document. In my experience, I have had to enable documents which have been disabled (I don't know how they became disabled however).
Edit 6/8: A disabled document will show up in the Disabled Items list just like a disabled add-in would. I have seen this happen several times over the years, however have not found a way to consistently recreate it.