3. Home remedies are the best when it comes to killing roaches. Some of the best known methods are listed below. 1  Boric acid in powdered form, mixed with sugar and flour, to kill, bait and hold the mixture, respectively, is one stop solution for all your problems.ome remedies are the best when it comes to killing roaches. Some of the best known methods are listed below. 1  Boric acid in powdered form, mixed with sugar and flour, to kill, bait and hold the mixture, respectively, is one stop solution for all your problems.