Which Sony reader did you buy ?
On my PRS-900 there is one option to delete books directly on the reader. Or you may install the Sony Library software, coonect the reader and delete the books using the library software.
About the manual. Have you tried Sony support page like http://esupport.sony.com/US/perl/mod....pl?mdl=PRS900
? You can download the manuals for all reader from there.