how do you disconect a toilet?

[stevesue]

We are putting in new floor boards in the bathroon. How do you disconect the toilet?

[Clanad]

Assuming similarity with those here in the U.S., it's reasonably simple.
First, turn off the valve on the water supply line and flush the toilet. Remove any remaining water in the tank, then disconnect the water supply. Simply unscrew the supply line from the bottom of the reservoir.
Once the tank is dry, remove it from the lower, seat part. There should be two bolts in the bottom of the tank securing it to the lower part. These are usually brass and will take a wrench to loosen the nuts on the bottom of the tank. Lift off the tank and set aside.
On the bottom, ceramic flange on the floor under the seat will be a cap about two inches in diameter, one on each side. Pry these caps off with a screwdriver. Under the cap are nuts attached to their respective bolts. Remove these. Now, gently rocking the entire seat/lower assembly from side to side, pull straight up on it. It can be fairly heavy so you might want some help. It will come loose and set it aside. Near the back of the entire structure you've just removed, you'll see a hole in the floor where the waste water exited when flushed. There will be a messy looking wax ring surrounding the actual pipe. Remove this ring and thoroughly clean the entire are. You'll need a new ring when you reinstall everything. If, by installing the new floorboards, you elevate the floor above what it is now, you may need a wax ring extension. If you're just replacing rotted subflooring, just the standard wax ring will do. (Stuff a rag in the hole to keep the odd hammer, bolt or small dog from falling in).

Caution... when reinstalling the bottom on the two bolts, don't over tighten since you can crack the porcelain around the holes... real expensive real fast is the word of the day after that...
Best of luck!