Sohrab,
Well, your question has a lot of unknowns. The one thing that is relatively safe to say, if your indexes do not use the fields in any way, shape or form (and be very careful here, just because a field is not specifically indexed on, does not mean it's not part of another index expression...) If it is not, then, no, it will not have an impact on any index itself.
On the other side of the coin, I'd be very careful to fully understand what you are getting into. Even deleting a field that is "Blank" might cause the application that it is associated with (assuming there is one), not to work, because it's looking to display that field in a form. My advise is, if you really want to get rid of it, and test it, make a copy of the original table first. In fact, I'd say, copy the whole application, and data onto another machine that can not be confused for the main application. Delete the field there, and run your application. Test all areas, see if it blows up. If it does, then you know you can't delete that field. In the mean time, you've affected no one's life adversly!

It's what testing environments are all about. You can play, and break things there, and not have to worry about it at the end of the day. So, go, chop away. (But move it, and back it up first.)
Best Regards,
Scott
"Everything should be made as simple as possible, and no simpler."
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