Want to add my old laptop hard drive to my new system

I'm unsure if this is the right place to ask, but I have a hard drive from an old laptop that I added to my new computer and was wondering if there's an easy way to delete all of the windows files from it while retaining my files so that I can keep my system more organized.

As far as I can tell, the simplest but least clean option would be to manually delete anything unnecessary from the drive's system folders. Any tips would be appreciated.