How do you shut off alarm on g500a watch - Casio G-Shock GW500A-1V Wrist Watch

Hold A, and B and press C, mine shut off

Press Mode, start/stop, and reset at the same time.

press the "mode" button to reach the alarm setting position and then press one of the other buttons to turn the alarm off. (as I don't know which watch you have, you will have to experiment to find the correct button).

I haven't been able to find instructions for your watch but since most watches operate in a similar manner try the following:-
(I assume that your watch had an lcd screen.)

Press the mode button until you reach the alarm setting feature, "AL"? there may be one feature that is specifically for hour repeat "HR"? use one of the other buttons to turn it from "ON" to "OFF".

Press the mode button to return to normal operation.

Some experimentation may be required.

using the mode button (lower left, go to the alarm. once at this screen, hit the "12/24H" button (lower right). now hit the "adjust" button (upper left), that should toggle the hourly chime on and off. you'll see the bar next to 'SIG'. when it's lit, it's on, when it's blank, it's off.

On RLX1003 Hold S1 ( bottom right ) and then press S2 ( Top Right ) to toggle through the options ( Alarm and Chine )

Okay I have this module so here goes.
Start from your regular timekeeping mode (use lower left buttin to cycle through until you get to the normal time display).
Press 'mode' button (lower left) once. You are now in alarm mode.
Press lower right button to cycle through the alarm modes. The cycle goes: hourly beep on, timed alarm on, both on, neither on. You will see the corresponding icons (a ripple icon for hourly beep and and a bell icon for the alarm) appearing/disappearing in the top left of your display as you cycle through. So if you are in hourly beep mode now you probably need to press that lower right button 3 times to get to 'neither' alarm being on.
Press lower left button to return to normal display.
Hopefully - enjoy the peace!

Press mode until in Alarm Mode
Press Receive until alarm # shows AL1-4 or Sig
Press Time/Memo to change alarm on or off. On is shown by indicator next to alarm name.

just go into the alarm menu and simply press the "reset" button once, and it should reset the alarm also leave the function off.

Hey Try this link you will find all the watchs, look for yours click on it and you will have the option to dowload the manual http://www.timex.com/gp/node/n/237130011/105-9974488-9618819?ie=UTF8&timexBrand=core have a good day