This article will cover the procedure to take if you are having difficulties removing the strimmer head.
The hole visible in the image below is where you will need to place a long thin item. We recommend a screwdriver to be placed into the hole as this is ideal to hold the head in place. The screwdriver will go through the metal guard and then the metal gear. Please ensure the screwdriver is firmly through the first hole and locked into the second. Once this has been locked into position the head should now be able to be twisted and removed.