When Orwell actually arrives at the location where the supposedly rogue elephant is to be found, it is immediately clear to him that he should not shoot the elephant. There are plenty of reasons that he gives for this, as he is able to look more objectively upon the matter than the crowds of Burmese around him who want him to shoot the elephant. Note what he says:
It is a serious matter to shoot a working elephant--it is comparable to destroying a huge and costly piece of machinery--and obviously one ought not to do it if it can possibly be avoided. And at that distance, peacefully eating, the elephant looked no more dangerous than a cow.
The two main reasons that Orwell gives for not wanting to shoot the elephant are therefore the way in which, for the Burmese, an elephant was considered not a wild animal, but a tool, or a means of livelihood, and therefore it was a "huge and costly piece of machinery." Secondly, Orwell also feels that the elephant does not at all look like it is dangerous. On the contrary, he compares it to a cow to emphasise how peaceful and tranquil it appears, These are two very strong reasons for not wanting to kill the elephant, and it is obvious that there appears to be no need to kill it.