[ESS] modifying key bindings

[Jeff G.]

Hi all,

I apologize if this is really basic, but I would really, really like
to get rid of the key binding C-c C-b which corresponds to
ess-eval-buffer.  I keep hitting it by accident when trying to type
C-c C-n.   With longer buffers, this can be a serious pain.

After extensive Google searching, I took a shot in the dark and added
the line (global-unset-key (kbd "C-c C-b")) to my Preferences.el file.
 No dice.

Any ideas?

Thank you!

Jeff