Link your iPod to your computer, open iTunes, in there you can view what's on your iPod and modify what is on it. Not rocket science.
yeah
if you want to manually manage your music...
hook it up through the usb cord... on the left under the icon for your ipod hit music
it will open up all the music on your ipod... you can delete from there
OR
you can simply delete songs you don't want from your itunes... hook your ipod and sync it... but be advised if you do this the songs on your ipod will be exactly the same as the songs in your itunes when you sync it... so if you have songs on your ipod you want that are not in your itunes... you're gonna lose them