Removing deleted apps from itunes

I am recently the proud owner of an iphone 4!! I downloaded a few apps onto the phone and then they were synced to itunes on my mac. I then deleted some apps that I didn't want and saw that if I didn't uncheck them in itunes that they would go back on the iphone with the next sync. I would like to actually remove the unchecked ones OFF my itunes but I can't figure out how to do this.....anyone?