Pretty much any wrought iron railing shop or steel fabrication shop that does any stairs can make this for you. You can have spindles 4" o.c. or tabs to attach glass or plexiglass, or a combination of both. You don't need an architect to draw you a pretty picture. This is engineering, but someone who builds stairs and railings will know exactly what to do. Basically, you can make it removable by removing a few lag bolts. It is no big deal if it is a welded steel frame. Depending on the final design, and how often you need to remove it, plexiglass could be lighter than real glass, and allow the railing to stay in one piece when removed. Or, the railing could be made in two or three sections, so you only need to remove the lower section(s) when moving furniture.

We had a staircase just like yours in the house I grew up in. One year we had our family Christmas party with a folding table buffet of food set up along that wall below the stairs. After my uncle's girlfriend's daughter fell off the stairs into the punchbowl and flipped all the food onto the floor, my dad spent the next day at Hechinger's (a local hardware and home repair store before Home Depot moved in) getting a very basic iron railing that was installed the following week!

Here is a simple design that would be made from square steel tube and a wood top rail that could be taken apart in 3 sections.

Fred, how would it be removed?

Just take out a few lag bolts that hold it in place......more elaborate 'sleeves' and 'pins' could be designed quite easily if you anticipate needing to remove it more than once a year.

I can't draw "glass" on my phone, but the panels could separate at the red lines, and either one large panel or a few narrow panels of glass or plexiglass in the big holes would just stay in the steel frames when you remove them.