online-only file

The Windows 10 April 2018 update got me!!! Long story short, I had to have it re-installed and now I am putting everything on my computer that I had before.  I installed adobe for pdf viewing but now when I go to delete any of them it says an online-only file will be permanently deleted without being placed in the recycle bin.   What is an online-only file?  It has never said this before.