Bill asks Sam to reduce the ransom amount because he believes that it would be cruel to expect a father to pay so much for his ill-behaved child's return. It is also likely (based on his interactions with Johnny) that Bill has little faith Johnny's father will pay the two thousand dollars they are requesting.

To placate Bill, Sam asks for a ransom of fifteen hundred dollars in his letter to Ebenezer Dorset. However, Bill's fears are realized when he and Sam receive correspondence from Johnny's father. In his letter, Ebenezer Dorset tells the men that their ransom demand is much too high. Instead, he makes a counteroffer, requesting that the men pay him 250 dollars cash in order to take Johnny back.

Ebenezer finishes up his letter with a warning: the men had better bring Johnny back at night, so that the neighbors do not see the boy returning. Ebenezer hints that the neighbors will not be too pleased to see Johnny home and might take out their anger on Bill and Sam. This humorous story ends with Bill running as fast as he can towards the Canadian border after paying 250 dollars to Ebenezer Dorset to take Johnny back. 

Why does Bill ask Sam if they can lower the ransom demand in "The Ransom of Red Chief"?

It's at this point in the story where Bill and Sam start to realize that maybe it wasn't such a good idea to kidnap little Johnny after all. Ever since they snatched him, he's been nothing but trouble. He drives the two hapless criminals insane with his brattish behavior, taking control of a situation in which he's supposed to be the weak, helpless victim.

Johnny's becoming so much of a pain in the neck that Bill just wants him off his hands as soon as possible. That's why he asks Sam if he should lower the ransom; the lower the asking price, the quicker they can be rid of the annoying little brat once and for all. In the end, though, it's Bill and Sam who end up paying the boy's father to take him off their hands. Probably for the first time in criminal history, it's the kidnappers who pay the ransom.

Why does Bill ask Sam if they can lower the ransom demand in "The Ransom of Red Chief"?

Bill wants to lower the ransom amount because Red Chief, the boy who Bill and Sam have kidnapped, is terrorizing them, particularly Bill. Red Chief continually lets out blood-curdling war cries, and he also threatens to scalp Bill by sitting on his chest and holding a knife to his head. Later, the boy drops a hot potato down Bill's back and smashes it with his foot. Red Chief threatens to hit Bill with a rock, and then tosses a rock that hits Bill behind the ear. As a result, Bill falls into the campfire. Red Chief seems in no hurry whatsoever to get home, as he's having a grand time camping out with Bill and Sam. While Sam wants to ask for a $2,000 ransom, Bill begs him to lower the ransom to $1,500, as Bill doubts Red Chief's parents will want to pay the higher price to get their rowdy and troublesome son back.