Although placed as other blocks, reinforced platforms do not create a "back wall" below them, and thus "float" where they are. (This really only matters above bedrock, the permanent stone back wall.) They are removed most efficiently with an axe.
As they are made of wood, they will burn if lit with an ember or if placed to close to a campfire.
Prior to version 1.1, reinforced platforms were known as wooden platforms and required only one wood to create five platforms. Worlds started before version 1.1 had any existing wooden platforms changed into reinforced platforms.