Please Help With My Game

I am making a game similar to 2048. If you have ever played the 2048 tile game, then you have an idea of what I want to do. I need to be able to put two matching tiles together to create a new tile with a higher number while the original two tiles disappear.

Right now, when I put two tiles together, the new tile is created, but one of the originals still remains.

Here is a link to my game, what I have so far:

I hope this gives you an idea of what I am trying to do. Thank you for your help.