Who Cut the Beam?
Why not just change your mind set about cutting the beam. Cutting any beam is a Bad idea. What about just trimming the hollow core folding doors to fit into the opening. Obviously a very bad choice had been made here by an inexperienced handyman. This photo was taken by me during one of my home inspections this past week.
When adding enhancements to a basement, such as door to close off storage, the installer should never, ever cut the supportive, structural beam. Sometimes just drilling into the beam may be frowned upon by the manufacturer. The system installed in this house consisted of I-Beam joist with parallel strand lumber used for the beams. In this case a repair had been prescribed by the manufacturer for the damaged component that had been sistered over the beam. The wolmanized verticle 2x8s are not structural but were merely placed there to fill the gaps on the either side of the doors.