Lets see if I can explain a spiral staircase without using my hands !
There is a horizontal strip at ground level which holds the base of the skirting. This is nothing more than a U shaped profile strip, nailed down, that the skirting sits in. Leave it alone unless you really have to change it out!
Across the top is another horizontal strip which hides the top edge of the skirting - this is the key to removing it! Think of this as an upside-down V shape, with one side secured to the side of the home, and the other side holds the top of the skirting in tight.
Place one hand under the edge of this top piece and lift it carefully - it will bend outwards, allowing you to reach under and pull the top of the skirting clear. Be careful not to bend it too far, or it will snap, especially with older skirting! Once you have it started, pull out the length of needed skirting so it is clear of the top strip.
The skirting itself consists of panels that hook together by the simple method of rolling the last ½ inch back on itself - forwards on one side and backwards on the other. Once you have a few panels exposed, you will quickly see this. Simply grasp the panel by the top edge and lift it out, and repeat for any more panels that you need to remove.
A word to the wise ... quite often the ground is not level, so each panel will be cut to go into a specific place. Mark the panels as you remove them you you can put them back in the same place later! Imagine if you will a jigsaw where all the pieces are the same shape and same color, just different lengths!!!
Hope that helps!
DaveyB