Open the camera application. Tap the 3 dot Options menu, choose the Settings wheel and change your options there. You can also put the phone on silent or vibrate mode, which will mute all sounds including the camera.
If you need any further assistance with this question, please contact the Sonim Customer Experience Center at 1-833-MY-SONIM (1-833-697-6646) or email us at [email protected]. We are open 24 hours a day, Monday-Friday and we will further assist in troubleshooting.