You cannot remove fields from a table when this field was already published. You will have to set the "ObsoleteState = Pending/Removed" and define an "ObsoleteReason" for those fields. This will essentially remove them from your data structure, since you can't use them anymore (will throw errors or warnings in the code), but you cannot remove those.
You also would have to make sure that the data upgrade routines clear those fields and move the values to the proper new fields - if you have any.
