Hi Samuel: You can get back to the default views by following the steps listed below. Studio stores the customizations in a separate inherited view that can be deactivated or deleted if you want to revert the customization.

Here are the steps involved:

1. Enable Developer mode by going to Settings > General Settings, scrolling all the way down and clicking on the "Activate the developer mode" link.

2. Navigate to the Odoo screen you modified and click on the "bug" icon on the top of the screen.

3. Click on the "Edit View: TYPE OF VIEW" item in the menu. The TYPE OF VIEW will depend on the view that are viewing. For example, in this case it is "Edit View: Kanban" because this is a Kanban view.

4. Then select the "Inherited Views" tab and the view that starts with "Odoo Studio: ..." like so. This is the view that Studio created.

5. Archive the view (i.e. make it inactive) by clicking on the "Active" toggle button. Save your changes. Reload the page. You should now see the default screen after reloading the page.

Hope this helps.

Yes, it's on a test db. Thank you for your quick response!

I'm assuming you were working on a testing db.

SHORT: If you had a copy of the db you can restore that. If not I would suggest a brand new db. 

LONG: I don't know of a way to restore "only" product.template, as there are several modules that may use/contain it, for example mrp (needs it) or purchase (uses it). And there may be other modules that use it on a not so obvious way. So in that case you might need to delete and reinstall all those apps, and may still not work if you don't uninstall your studio custom. You can try. I would go for a clean restart tho.

Hope that helps.