Now remove the plastic rim on the left by pulling up on it.
Now you need the alen wrench to loosen the screws in the lagsields to remove the CPU(s). You do not need to remove the screws.
Once you have them all loose gently pull the CPU(s) up to unplug them. This will take some effort as the lagsields "drag" on the holes some.
Be very carefull not to pull up at an angle, you will bend the lagsields, or worse damage the CPU connector(s). If it will not pull up stright all of the lagshields are not loose!
Here is the bottom of one of the CPUs and what the board looks like under them.