I'm stuck trying to remove my SHIMANO Nexus FC-C6000 Crank from the SHIMANO BB-UN55 bottom bracket. I've removed the bolts fine but can't get the cranks apart. Any suggestions?
You need a crank puller. It threads in to the crank arm, and presses on the bottom bracket spindle to pull the arms off.
A video here from Park Tool on using their crank puller: