About the usage of whether to.....or not [closed]

I believe all are correct but perhaps a bit stilted, or less than comfortable.

It would be more natural to say Whether to kill him or keep him. The missing to would certainly be understood. This would be common for spoken English or written as a quote from someone. Perhaps you should ask him. He may have a better answer.

Whether to kill him or to keep him is a phrase that functions as a subject in 1 and an object in 2.

Whether to eliminate the second to in the phrase is a matter of style.

But 3 is incorrect. The phrase is unattached to anything; it would be grammatical if it were changed to whether we kill him or keep him.”