Deleting controls from Field Chooser... disabled!?

[RJ]

I'm trying to delete some controls from the 'Field
Chooser' list so that they don't appear on the Form
printout. However, when I try to do so, the 'Delete'
button is disabled and therefore prevents me to do this.
These controls are neither used or bound to anything on
the form. Is there another way to delete them?

Thanks for any insight on this.