Remove an under counter kitchen cabinet

I need to remove the single, under-counter kitchen cabinet (indicated by arrow in the photo on the left hand side) so that we can install a new boiler. However, I cannot get it out. There is a single attachment site that I cannot see which is securing it to the unit on the right (this unit needs to stay as this is where the oven goes). The unit to be removed will be discarded, so can be damaged if needed.