If the tool is recommending you to combine the files into 1, that's outdated information, in fact combining files can actually make your site load slower (case study here: https://speedboostr.com/concatenation-case-study/).
In any case, to check to see if you have any extra scripts loading that shouldn't be, you'll want to do what we at Speed Boostr (Shopify optimization agency) call an App Analysis.
What you want to do is:
1) Look through your main theme files and see if there is any leftover code from apps you uninstalled. This is common because when you delete an app, Shopify immediately revokes access, so the app can't cleanup any code that it added to your theme. The main place you'll find old app code is theme.liquid and product.liquid (or it's sections / snippets).
3) In our full app analysis we also analyze slowest / heaviest loaders and look for errors, bottlenecks, and conditional loading opportunities, but for snuffing out extra files my points #1 and #2 is handle that.
Good luck on the investigation. If you find it too time consuming and want to hire an expert, feel free to reach out to speedboostr.com/contact. My team does stuff like this on a daily basis.