Rae from Shopify here. Thanks for reaching out!
This typically comes down to the apps in question, which data you're hoping to keep, and if they're third-party or Shopify-developed apps. In general though, usually when you uninstall an app, any data from the app that wasn't coded into your site will be removed. You can find more information on this here.
You mentioned you're using some paid apps that you want to remove. If these are third-party developed apps, I recommend reaching out to the app developers about this directly for more information. Since they fully support their apps, they'll be able to clarify what data will remain on your site once their apps have been uninstalled.
However, if you're instead looking to do this with a Shopify-developed app, can you please confirm the below details:
Once I have this information, I'll be happy to help look into this further.