This question already has an answer here:
When I read the answers to "What was Ash trying to do with the magazine?", I was wondering why he would use a magazine at all to kill her.
As an android, he is stronger and faster than humans. He could crush her throat by choking her. He could crush her skull with his bare hands. He could grab something and quickly stab her chest far faster than it would take to roll up a magazine and stuff it in her throat. He could move his hands fast enough to break her ribs inward and puncture her chest organs. He had so many other options that were quicker and more likely to succeed.
Edit: This is not a duplicate of "What was Ash trying to do with the magazine?", since that asks about Ash's intentions, but this one asks why he uses an inefficient method to kill her. None of the answers there mention that Ash could have used a different murder weapon/technique.