Yes. I recommend that each customer build out their own viewer, but using the sample is perfectly fine, and you can hide the model tree by editing some of the JavaScript UI classes that are built into the sample viewer. Specifically you need to do edit is web_viewer_ui.js in the web_viewer/src/js folder. You’ll want to comment out lines 1052 – 1056. Once you do that, make sure to clear your browser cache so that the new JavaScript file is pulled in when you reload the page. This is as of 2016 SP2. You may need to investigate this further in future releases as this code is subject to change.
Edit: comment out this._modelBrowser = new Desktop.ModelBrowser… and it is never displayed