The easiest way is to create a master database in which you install the modules you want and without data in it. But you will have to do  the fulll customising in it. When you want to test, just create a duplicate of the master database and work in the duplicate.

If you have created a lot of structures, products, etc., you can easily export them from the database you have into the new db via .csv files.

And in the settings, you have the list of modules installed, so that this os only a few click to reinstall