You can either de-feature the part. Or, you could open the surfaces folder at the top of the tree, RMB on the surface and 'insert into new part'. This will give you the surface alone but will a link to the original so that any changes made to the original will be reflected in the new file. You can break that link if you want to.
suppress the fillet it will begone but not deleted, then save as a step file.
You can control select the faces you want in the step file the save only those.