After importing the shape from the STEP file, you can delete the hole or fillet in the shape. By this function, the shapes without operation history data that is created other CAD can be edit/simplified easily.
Import solid data from STEP file and switch workbench to Part workbench.
In the 3D view, select the face of the shape (hole, fillet, etc.) you want to delete. And execute Defeaturing tool or select [Part]-[Defeaturing] menu.
If you need to select multiple faces, you can do so by holding down the Ctrl key while selecting.