To remove the skirts of the outdoor spa, you have to follow the steps shown in the picture, normally the skirt that needs to be removed for the electrical installation is the one under the control panel:
You can use the hook included with the SPA, an Allen key or similar.
On the side of the skirt there is a strip of aluminium, insert the hook and prise it out.
Remove the aluminium strip (to reinstall it, just put it back on and tap it carefully in order to avoid damaging it).
Unscrew and remove the rectangular puller underneath the skirt.
You can now remove the skirt by detaching the lower part and sliding it downwards.
To reinstall it, just follow the same steps in reverse.