That question concerns me. What do you have for tools? And what do you know about 12V Battery systems?
Mechanically, its a piece of cake to take off the cables, just start waving the correct size wrench at them.
But lets start more simply, if this comes off as condescending, I apologize now, but that question really does scream neophyte to all things mechanical and electrical.
When working around the positive side (+) of the battery, its best to disconnect the ground side (-) first. Assume anything metal is ground, if you accidentaly touch a wrench from the (+) to anything (-) you will get an instantaneous flow of amps in the several hundreds (to the limit of the battery). Think of amps as the powder in a firework, very lower powder, like a cap gun, and the accidental brush with ground goes snap and you get a little blue spark. But when you have a large amount of powder, you can blow things up KABOOM!. At hundreds of amps, if you were to drop your wrench between the (+) and the (-) terminals of your battery, the battery terminals will instantly melt in giant blue arc that sounds like a gunshot and melt a chunk out of your steel wrench, and if there is a gas leak in the battery and there is Hydrogen gas present, blow the battery up spaying sulfuric acid all over you anything else in the area. These are facts. I am not telling you this to scare you like the bogyman; I have actually done it, all but the blowing up of the battery part anyway. The rest was scary enough.
So, shall I continue your education Paduan? Or have I insulted your intelligence?