The hard disk in bay one is my main working hard drive and a hard disk in bay two is a backup drive on a 2009 Mac Pro desktop computer. I'm running OS X Yosemite version 10.10.5. There is no available memory in bay two so I want to delete some of the files. When I try to do this from the hard disk in bay one, the following message appears: "The operation can't be completed because one or more required items can't be found. Error code -43." Thanks for any tips on how I can resolve this error message in order to delete files from the hard disk in bay two.