I have an old Bible from grade school that is of no use to me (it has been torn up and written over). Is there a proper, respectful way to dispose of a used Bible?
There are different proper, respectful ways of disposing of a used Bible, but there is no specified way. I have heard and read of people burying their used Bibles and others recycling them so that the pages can be turned into something new and useful (perhaps another Bible). The approaches to disposing of a used Bible vary, but the approaches are driven by respect for what people are discarding. You can dispose of your old Bible in any number of ways that do not bother you or your conscience.
To me, your concern about what to do with a used Bible reflects a love for the Word of God in general (Psalm 119:105-112). That is a wonderful attitude. God bless you.