Cabinets & installing new flooring

Has anyone any experience and insight regarding the removal of the sink cabinet to redo the tile flooring? How difficult ... tricks ... etc.. There has been a leak under the sink in the used unit we just got that has resulted in the flooring buckling up some ... so am contemplating having to remove the tile so that I can get to the swelled up plywood, or whatever is under there that swelled up, and be able to grind it down to the level plane for new time installation. Also the cabinet is somewhat dilipated. so this would be a good time to replace it.

Under/inside the cabinet is some sort of a junction box that is dangeling down. Has one wire in one side and several in the other side. All components work but there is nothing on this box to indicate what it is for. It's about 4 inches long by 3 inches wide. Any idea?

Thanks
doon