The crankarm is self extracting indeed. So the only tools that you will need are a couple of hex keys - 8mm and 10mm. Please refer to the tutorial below for more info:
Removal of the left crank arm
Use a 8mm hex key to unscrew the bolt that holds the crankarm in place as shown in the image below (image 1). Note that it will require a lot of force to come loose as we use thread-lock for extra safety. An impact driver can be used for the job as well.
As the screw comes out, it will push against a black metal nut that drivces the crankarm out.
image 1Installing the new crank arm
Hold the crankarm in place and screw the 8mm bolt (image 2,3 & 4). Please use threadlock to secure it in place. And by all means do try to tighten it as much as possible. It's a good idea to use an impact driver to ensure that the bolt is tightened well.
Now put the black nut (cap) and secure it with a 10mm key (image 5). There's no need to overtighten as with the bolt. Just a firm fit.
image 2image 3image 4image 5