Hello how do i delete the whole library on it and

Hi gymgirl,
Probably the simplest way would be to format it. Go to Settings --> Common Settings --> Format to do this. This removes everything on the mp3 player, right from data to the current time.
If, however, the idea of formatting scares you (as it does me), just hook up the player to your computer, double click to enter the Walkman device from My computer, and delete all the contents of the folders MUSIC and VIDEO. But watch out - DO NOT DELETE THE FOLDERS!