Tips to update theme and remove ALL app code

I have a store that is 9 years old. It has been through MANY theme revisions and has a HUNDREDS of apps installed and uninstalled. It also has tens of thousands of old inventory items. The current theme is old, prior to the 2.0 revision. We are going through some big changes with the website and I basically want to start over by installing a new theme and I want to make sure that ALL old code from all the old apps is totally gone. I also want to remove all inventory items in the admin except what is currently in stock.

What is the best way to go about this? If I download a new 2.0 theme and edit it while I keep the current website going, then publish to the new theme…will a lot of the old garbage app code from old apps remain? Do I need to uninstall all apps, before publishing the new theme? Then if I want any apps for the new theme, I can reinstall them?

Thanks for any information you can provide! I’m just trying to get a good plan together

@Stephen34 - the new theme will not have any app code till you add it, so you can keep old code, install new theme and it should work as per your requirement