Extracting the code from Keras
If you are looking for a way to compile code written for the Keras API to code only using the Tensorflow API, there is no ready-to-use solution for that. And I cannot see any good reason why someone would want to do that in the first place...

You can simply look at the Keras backend source code for Tensorflow and rewrite your entire implementation. But once again I don't see any valid reason that would make this worth it.