You need to take a step back and start with the simple stuff.
Before working out how to turn the ABS off, you need to work out if it's connected / working.
First off, what year is your bike? - Do you have servo (power assisted) brakes or not? (I'm assuming not as you still have full brakes - not just residual - even when the ABS isn't working - is there a whine from under the tank when you apply the brakes?).
So forgetting the ABS button, what happens with the ABS lights during a normal starting procedure - answer the following questions:
1. Ignition on, before you press the starter button - what are the ABS lights doing?
2. Press the starter button, start the engine and ride off - what are the ABS lights doing?
3. When you ride off is there a brief chattering noise and a clunk from under the tank?
After this, post the answers back here and / or read this page - it has some very useful information regarding ABS:
http://www.largiader.com/abs/absfault.html