أحسن الله-Ustadh. I took two books from the masjid shelf that were from deviants and replaced them with Salafi books. Scholars warned against one of the books.What should I do with them: return, keep, or dispose respectfully? بارك الله فيك

Do not destroy them yourself, because books placed in a masjid are for its people, so give them to the masjid's imam or administration and tell them which one the scholars warned against so they remove it. Adding good books to the masjid is a good deed, may Allah reward you.