Okay, I'm someone who should not be muddling too much in the databases... hopefully I didn't mess up anything when I went in to get rid of some incorrect addresses for our own location.
In Events>Location, we had a few incorrect addresses in our drop-down list (4549 instead of 4945). We did not want someone to accidentally select one of these.
To remove them this is what I did: I looked at the location in all events (in Manage Events), including past events, to make sure none of the incorrect addresses were being used. Depending on the number of events you have, this can be a bit time-consuming, but why have wrong info in your database, right?
Through Control Panel, I went to phpMyAdmin and selected database from the lefthand side. I then did a search on the street address (with "match exact phrase" box checked, and all tables selected) to find the table this was in - civicrm_address.
In the search results, you can scroll down to see the results in the table. I checked to make sure there was no contact_id associated with the address that I wanted to delete... identified with NULL. (It is our own address, albeit incorrect, and no one lives at the incorrect address... it's a corn field!), so no contact would have it listed. I deleted it. I then went into our CiviCRM and checked the location drop-down list in a current event (Manage Event), and incorrect address is no longer in the list.
Not sure if this is a recommended way to do this, but the incorrect addresses are no longer in Event Location drop-down list.
I am not sure if I did find an incorrect address in use in a past event if I would be able to change it, or if that would cause other problems.