worktop reset of joint

hello people,
have been asked to sort out a laminated 28mm ikea worktop joint which is not flush at the front edge.

its a mason mitre job with bolts and visible colorfill in there,the question is on the colorfill itself..

after the bolts,what is the best way to carefully seperate the colorfill binding in order to reset the joint ??

any advice appreciated,cheers