Re-Model Imported Part

I have this imported part that's a back for an office chair.  It is modeled with 7 horizontal "channels".  I need a "smooth" plain back w/o the channels.  I don't know of a way to remove them from the imported part since there are no features and re-modeling w/o the channels has proven to be beyond my capabilities.  Can anyone offer any helpful hints on how to do this?

Thanks,

Steve

SolidworksParts And Features