The case is a teacher Alice that has published some material and later on she wants to cease publishing it.
Other teachers, Bob and Cal, might have referenced the original material, if they found that the content fits their course.
On top of this, a number of students might be using the material, which means things like just now they are sleeping but tomorrow first thing in the morning they will continue using it.
Then Alice decides to stop publishing the original material.
Perhaps she had developed an online course and now the course is being taken down, or maybe she's replacing the original material with a newer version.
If Alice is taking down her course the course materials that are referenced by other courses (maybe by Alice herself) should stay there so those other courses, or the students, can still peruse it.
The material should vanish (archived) only when it is not referenced and after a while, like one year.
If Alice is replacing the material with something newer, then it should be handled as above and additionally the system should tell Bob and Cal that they are pointing to an outdated item giving them the opportunity to update.
The students should also be warned, upon opening the content, that they have the option to switch to the newer version.
Another case is if the material was found to be inappropriate, harmful, or whatever so that there is value in taking it immediately.
In this case it should be blocked and deleted immediately.
This is different from the other cases where the material is left in the server albeit dereferenced.