Delete PDFs from iTunes?

[ppfd]

I have various pdf files -catalogs, magazines,etc. I have uploaded into iTunes and then onto my iPad. Easy to delete from Ibooks. I cannot figure out how to get them out of Itunes though. I thought taking them out of Ibooks would do it but, no such luck.

 

[NoBoMac]

Select the device in iTunes, then look under "On My Device" in the left column?