How to replace uploaded files?

How do I replace uploaded PDF files? The Link Editor dialog is showing only 20 files. So how do I replace old files with new ones while still maintaining the same URL? In older squarespace versions, I was able to find the file, delete it, and then upload a new file with the same filename. This way, the URL didn't change and all links across my website to that file were maintained. Now, I have no way of doing this without changing every single link to the new URL of the newly uploaded file.

And Searching for a filename doesn't work either. The search only returns results from the 20 listed files.

Please help! 

Also, I wouldn't want the old files to continue to be indexed by Google. So there needs to be a way to delete them! This is basic file management functionality...

There seems no way to replace the file without changing its URL.

https://support.squarespace.com/hc/en-us/articles/205812748-Image-and-file-URLs-in-Squarespace