from what i know it means destroyed or obliviated or taken away. i.e. if something is completely eradicated ther is nothing left of it (well maybe a few remains...................... i hope that's what you were looking for. or in animals it could mean exstinct i suppose i.e. the dinosaurs were completely eradicated from this planet many years ago.
If you were found not guilty, your charge was dismissed, or you were found guilty, the charge will remain on your record until you seek to have it expunged.
Armed guards are essential to your success as a dictator, as they can dispose of unwanted rebels by shooting them. These armed guards should be placed everywhere, particularly in schools, hospitals and public toilets, so that unruly children, sick people and people who don't flush can be eradicted with ease. Good luck on your world conquest. :)