If you plan to use many of the pages and features offered by the template, then I suggest you to go with the option 1.
If you only want to use some specific pages or components and you already have an existing Angular app, then I suggest you to go with option 2 so you don't have to waste time deleting the things you don't need.
This template is itself an Angular app, so you don't need to create another one. You can use the template as a base for your app and just delete the pages you don't want and add the ones missing.
How to do this? Let's assume you want to use some form controls from the Extended Controls page.