In most homes, the baseboard molding is 1 to 3 inches in height and runs around the base of the walls. Occasionally, it's possible to have baseboards that are several inches in height or even taller than a traditional staircase riser. This style of baseboard is most often made of stained wood because the excess wood shows off the wood grain.
The problem associated with having baseboard molding taller than the risers of your staircase is that when the baseboards reach the bottom step, their height looks awkward. This situation, however, does not always have to be an issue. With smaller baseboard molding, it reaches the bottom step and is short enough to fit well below the bottom stair tread.
In most homes with baseboards, the baseboard ends at the base of the stairs and is joined with a baseboard-style piece of wood that runs diagonally up the stairs. At the top, the diagonal piece of wood ends and the baseboard continues again. In this case, the height of the baseboard does not matter, as a carpenter or experienced woodworker can customize the diagonal piece to match up with the top and bottom baseboards.
A suitable solution for high baseboard moldings is to install lower baseboards on the walls in your home that meet the staircase. Home improvement stores sell baseboards in a variety of shapes, sizes and styles. It's easy to find any given style of baseboard in several sizes. Select a baseboard style that matches or closely resembles the tall baseboard in your home and install it above and below the stairs.
To remove existing baseboards, slip a pry bar behind the baseboard and pull outward. Repeat this process along the length of the baseboard until you are able to pull it free. Measure the new baseboard to size and paint it to match the other baseboards in your home. Hammer the new baseboard into place with finishing nails, set the nails and fill the holes with wood filler. Touch up the wood filler with paint.