If I understand what you’re asking:
Once you’ve created your project, both the engine code and your project code will show up in the solution. To build just your project and not your project AND the engine source, either select it from the “build” menu or right click it under the pane on the left and build it from there. Do not “build solution” as it will build both your project and the engine source, and it’s not really necessary to build the source unless you’re making changes there.
If you’re asking if it’s possible to have ONLY your project and NOT the source in the solution, the answer is “you can’t”, as far as I know.