How do I clear iBooks download queue on OS X? I purchased a book but I don't want to download it on my Mac right now. I want to download it to my iOS device later. I paused the download. How do I delete it from my download queue without downloading the entire book?

I'm using OS X 10.10 " Yosemite" but hopefully someone knows of a generic solution for most OS X installs.
Deleting the iBooks cache in /private/var/folders/randomLettersNumber/C/com.apple.iBooksX did the trick for me.

An easier way at least on OS X 10.11 is to click a book in the download queue, select all, then delete. Unfortunately iBooks will ask you to confirm the deletion of each book download.