The fact that an apparition is not “approved” does not mean that it is invalid unless there is a specific ruling from the Church proclaiming it invalid. That is not the case here as far as I know. And as previously noted, all apparitions were unapproved at some point.
All appartions, even those considered “approved” are non-binding to belief. Different people are touched in different ways by them and even an unapproved one may have deep effects on some people. I am aware of many people whose faith has been deepend by Medjugorje. Each person must discern, with whatever guidance the Church may offer, what weight to give to any personal revelation.
If you want to give them to a charity shop, I would see no problem with that. Who knows whose faith you might strengthen in some way.