This article describes how to remove misspelled words from the custom dictionary in the event that you’ve added them accidentally, while using the Spell checker in Windows Mail in Windows Vista.
Removing misspelled words from the custom dictionary
Click Start, type notepad.exe and press ENTER
From the File menu choose Open
Type the exact path and file name given below and click Open:
UserDictionary.lex is a plain-text file which stores the list of words that add using the Spell Checker in Windows Mail. After removing the misspelled word that you accidentally added earlier, make sure that there are no blank lines left by these deletions. Save the file and close Notepad.