If your sure your graft has taken, I would cut off the un-grafted side, as Chris said, lots of energy is going into growing all those new leaves on the ungrafted side, which is what you want to go towards your grafted side.
another option, is you can also put a graft on that other side, with the same variety or another, then you will have two branches already.
Have you had any growth on the grafted side yet?
I am guessing this root stock is Gomera, I have seen so many pictures of Gomera and those big purple / copper leaves, correct?