Okay, first...
...read what perderabo said
Pay special attn to the parts about not having enough information about your problem and using the "Post A Reply" button instead of the "Post New Thread" button.
Secondly...
...
read what I asked
Here's the problem:
1) Dell makes computers, so that's irrelevant to your email addresses
2) Windows 98 doesn't just store your email addresses without using some program, so we need to know the name of the program storing your email addresses before we can help you. What program do you use for email?
I'm guessing Outlook or something similar. If you're using hotmail or yahoo and storing addresses in there, then you're gonna have to search those sites to figure out how to delete addresses, because in that case it has nothing at all to do with Windows.