Hi Terri,
The spell checker used in Project is the same as is used in all
Microsoft products. You'll need to edit the custom dictionary
through Word. From Word, Tools > Options, Spelling & Grammar tab.
Click the Custom Dictionaries button, select the Custom.dic file and
click Modify. You can then delete the error from the dictionary.
I hope this helps. Let us know how you get along.
Julie
Project MVP
Visit
http://project.mvps.org/ for the FAQs and additional
information about Microsoft Project