How to reset iBooks app in OS X 10.10 How can I reset the iBooks app, I mean completely reset it to the version that was installed and when first opened, where the app would show "Welcome to iBooks" and "Get Started"?

I think I must remove a .plist file or something similar from Library, right?
In Terminal.app (found in the /Applications/Utilities/ folder), run this command and arguments:

/usr/bin/defaults delete ~/Library/Preferences/com.apple.iBooks


This will wipe the plist file, but may not trash it.

Now when you open iBooks, the settings will be back to the default.

This same command will work with other apps using the appropriate arguments.