difficult to delete downloaded software
I could not delete the third party software that I was already installed in MacBook Air. when I drag in to the trash it will again and again appear
MacBook Air 13″, macOS 10.15
If you purchased your Macbook Air new or refurbished from Apple there should be no third party software installed. If you purchased your MBA used and there is third party software installed the seller didn’t properly prepare it for sale. If that's the case you need to follow these instructions What to do before you sell, give away, or trade in your Mac - Apple Support