Octalink is Shimano's proprietary crank and bottom bracket design, popular on many mountain bikes and some road bikes. It is renowned for its stiffness and durability and is used by many of Shimano's mid-range to high-end products. Sometimes, it is necessary to remove your bike's cranks, such as when you need to replace your bottom bracket, or if your chain rings need to be replaced. Removing an Octalink crankset requires a couple of specialised tools, but can be done quickly.
Shift into smallest chain ring and pull the chain off the chain ring. Rest it on the bottom bracket shell of the frame.
Remove the crank arm bolts from both sides of the crank by loosening them with your Allen wrench.
Unthread the extractor fully from the mount on your crank arm remover. Then thread the extractor fully into the drive-side (left side) crank arm.
Thread the remover (the portion of the tool with the lever on it) into the extractor, until there is no more resistance and the crank arm comes off the bottom bracket.
Unthread the extractor from the crank arm and repeat the process for the other arm.
Make sure to thread the extractor straight into the arm. If you cross-thread it into the crank arms, you could damage the cranks.