After eating the last chametz on the fourteenth of Nissan, one should burn the remaining chametz in person, for it is more fitting to do it oneself than to assign it to someone else. It is forbidden to throw the chametz into the public domain, for this is undignified and is a desecration of the name of God in the eyes of the gentiles. The custom is to burn the chametz with the willow branches from Sukkot (see the book Chaim Larosh p.12). After burning, one should immediately nullify the chametz, using the language "[all chametz] that I have seen or that I have not seen". This should be recited three times, and it should not be done before the burning, because one has to own what they burn. If one borrowed a loaf of bread before Pesach, [an equivalent loaf] should be given back before Pesach too, but if not, it should be given back after Pesach. If one does not return it, this is a form of theft.