Hello, I'm Chris. I will do my best to answer your question fast and accurate using the info you have provided. Thanks for visiting Just Answer.Since you already have the intake off then you just need to unplug the knock senosr from the block and then remove the center nut/bolt and pry up on it to pop it off.
the problem is I don't see the knock sensor
It is under the lower intake manifold, I assume you just have the upper manifold off. See the below image.