When Gulliver lands in Lilliput, the Lilliputians do consider killing him pretty immediately. Given his size, he would eat and drink so incredibly much that it would be quite a chore and a huge expense to keep him fed. Further, he is so powerful that he could break free from his tiny chains and do a great deal of harm in the empire. However, the Lilliputians eventually decide against killing him because his dead body would be so large and cause such a smell that they are afraid it would start a plague.
Eventually, however, after the emperor of Lilliput turns on Gulliver, filing the articles of impeachment against him, a friend in the court warns Gulliver that they are now planning to starve him. In this way, they plan to reduce the size of his body almost by half, and this will make it more manageable after he perishes. Five or six thousand Lilliputians will then come and cut away chunks of his carcass to be buried far away, and in this way they plan to prevent the spread of disease, the fear of which is what stopped them before.