To remove the grip from your bike, simply loosen the two set screws on the outboard end of the grip and slide it off. The bar end plug should come with it, though you can also pry it out beforehand. The screws should use either a 2.5mm or 3mm allen wrench, and there is no way to identify which you have without fitting a wrench to it.
When you reinstall the grip, you want the flat 'pad' to be up high enough that it almost feels like it's too high, so it will properly support the palm of your hand. You only want to tighten these just enough so that the grip does not rotate. These threads are small and aluminum, so they can be damaged by overtightening, which would require replacing the grip. The bar end plug just presses into the end of the handlebar.