I have several t’fillin from my father, father-in-law and myself that I would like to know the proper way to dispose of. Is it to simply bury them or is there a religious process involved? Thank you.
They need to be buried. Tefillin need to be buried inside a vessel. The early sources mention in an earthenware vessel, today the custom is to bury them in plastic containers that will not decompose over time. Generally there is a local “geniza” organization that deals with burial and disposal of religious articles.
If the tefillin are still in usable condition, there are also charitable organizations that could make could use of them for others who can’t afford tefillin, or to a scribe who often needs spare pairs to loan to people.
see Shulchan Aruch O:C 154:5