There are four ways to turn StickyKeys off:
Check the StickyKeys check box in the AccessX main window.
Press the Shift key five times in succession (valid only if you've started OpenWindows with the -accessx option).
Press a modifier and any other key -- for example, Shift-x or Control-Shift (valid only if you've started OpenWindows with the -accessx option).
Press two modifier keys at once (see under "StickyKeys Settings").