It appears Theo's beneficent influence has drawn out your savage nature. I'm not surprised. Foul things tend to be attracted to the brightest lights.
Fortunately for us all, it's literally impossible to purposely destroy a face as beautiful as Theo's.
Oops, how did that last one get in there?
Anyway, what I was about to say was that Stiles will have to use subtler methods if he hopes to take Theo down, like maybe flying to London to pick up Jackson, and convincing Jackson to seduce Theo, and then waiting to see if their strong personalities clash the morning after their first rough night, and then pushing Jackson to stay as close as possible to Theo all night every night until Theo shows his weaknesses. And if he turns out not to have any weaknesses, Jackson could try to create some by making out with him a lot until he's got Theo conditioned to let his guard down. And then he and Theo could leave Beacon Hills and travel the world together, because honestly by that point it wouldn't even be necessary to try to kill him.