How should one treat left over old bread or challah? Halachically, how can it be thrown away?
Answer:
It may be wrapped up in a bag and then thrown away.
Sources:
SHulchan Aruch O:C 171:1, Chaye Adam 11:32, See Shu"T Hissorerus Hateshuva [2:183], Sefer Etz Hasadeh 11:1 in the name of Rav Elyashiv.