Welcome to TSG!
OE was setup to store it's messages under the User1 account. When that account was deleted, nobody told OE to store it's messages anyplace else, so they will still go to the same place.
To move the folder, in OE click Tools | Options, then click the Maintenance tab then click the Store Folder... button.
The path will be displayed, typical is
C:\Documents and Settings\User1\Local Settings\Application Data\Identities\{UID}\Microsoft\Outlook Express, where {UID} is a random string like {18FF48CA-91FC-4450-8853-6AD2EA99D834}.
Note the path -- you can copy it by clicking at the start, then drag the mouse to the right to highlight the entire path. Then CTRL+C to copy to the clipboard.
Close out of OE.
You can paste the path into the address bar in My Computer or Windows Explorer, or right into the Run box to open the folder. Just be sure to put quotes around it. Then click the up button to go up one level (C:\Documents and Settings\User1\Local Settings\Application Data\Identities\{UID}\Microsoft\), then right click the Outlook Express folder and choose copy. Navigate to the location you want the folder to be in (just change User1 to User2 for example, but you may have to create the Identities\{UID}\Microsoft folders first).
You can put it anywhere though, right in My Documents (C:\Documents and Settings\User2\My Documents) will make it easy to find. Once you are where you want, Click Edit | Paste, and the Outlook Express folder will be copied to the new location.
Now, start OE again, click Tools | Options, then click the Maintenance tab then click the Store Folder... button, click the Change... button and browse to the new location. Highlight it and click OK. It should tell you that a store folder exists, and ask if you want to use it, say Yes.
Exit OE, then restart. Double check the Store Folder location, and verify that all your messages are there. If everything is working, you can delete the original folder under user1 (or just rename it for a few days just in case).
HTH
Jerry