How to remove roller shade

Looks like a "wand tilt control".

http://www.fixmyblinds.com/vertical-blind-tilt-controls-s/91.htm

What could I do to reduce the amount of heat in the living room on sunny days without obstructing the view to the outside permanently?

What I find works well are traditional Venetian-blinds with silver-coloured metal horizontal slats.

Even though these are inside the window, they are still remarkably effective at reflecting sunlight out the window and preventing sunlight from heating interior surfaces such as carpets.

They also let air through when you open your window, which can be an advantage if the air outside is not hot.

By adjusting the angle, you can allow indirect light in to illuminate the room, and allow you to see out, while simultaneously blocking direct sunlight completely.

The traditional French system of external slatted wooden shutters and windows that open inwards is probably better - but that is not an option available to you.

A typical German solution is external slatted roller blinds that have small gaps between the slats which only close up when the blind is fully down. But these are usually installed when the building is constructed and are not easy to add afterwards.