take the bottom bracket cup off on the non drive side, put as many washers as you can get on the tapered part of the non drive side spindle plus a couple more,having used something softer to protect the bb shell first then put the crank bolt and tighten the non drive side crank bolt, this will pull the bottom bracket through the bottom bracket shell and will therefore eventually pull the chainset off. remember to protect both sides of the bb shell, its just a matter of using the right number of washers or similar.