Bontrager crank removal

The crankarm fixing bolts are normal, right hand threaded, so removal is anticlockwise. They do call for significant torque (43-48 N-m, one of your pics show). A simple "L" shaped Allen key used by hand may not provide enough torque to break loose the fixing bolt. Using a ratcheting wrench and a socket that terminates in an 8mm hex head might be the easiest solution. There are several different designs that get a hex head combined with a wrenching tool, and its something along that line that will give you enough power to free the crankarm fixing bolt. You may or may not know that after the fixing bolt is removed, a specialty tool called a "crank puller" will be needed to get the crank arms off the bottom bracket's spindle.

Here is Park Tool's crank puller with an instructional video on its use. If in fact your bottom bracket spindle is ISIS drive splines, you'll use the larger business end in the crank puller to remove the cranks.

Here is a link to a metric hex head socket set as an example of what I'm referring to in the first paragraph. Using these with a ratcheting wrench should allow you to deliver the power necessary to loosen the fixing bolts.