It is true there is an option in the camera app where the flash can be disable or enabled. However, users sometimes forget to switch it off when they try to take a picture secretly and sometime when they want to take a picture with the flash but it goes off because they forgot to turn it on therefore ruining the fun of taking pictures.
This tweak called “NoCameraFlash” developed by Tom Brek, will help to disable the flash during a photo shoot regardless of the flash setting in the camera phone. Even if the camera has the flash set to “on” or even “auto”, with this tweak installed it overrides the setting and keep the flash off. This tweak becomes handy in situation where you want to be discrete or want to make sure the flash doesn’t go off without taking a look at the settings and make sure it is off in your Camera application. It is like an added layer of security to the Camera application when you want to go unnoticed and keep the flash off.
This tweak has a preference pane on the Settings menu where you can easily disable or enable the tweak. No other configuration is required for this setting. This tweak works both for the Camera application and the camera grabber on the lock screen.
This tweak is available on cydia and can be found in BigBoss repository.