how to mute camera sound

ANIL is actually correct. You need to have root access first. In some phones, it is in system/media/audio/ui look for the file camera_click.ogg and camera_focus.ogg back 'em up first before deleting them just in case you want them back in the future.

DELETE SHUTTER SOUND FILE FROM ROOT FOLDER .

Check camera settings if there is option to turn off shutter sound. If there's none, just put your phone on silent mode.