The startup music that plays when a device turns on is standard. This is pre-installed by the manufacturer and can not be removed. The only way it would be silent when the device turns on is if the ringer is on silent. To adjust the ringer volume, press the volume keys (located on the right side) Up or Down.
Putting the phone on silent does not help. I have the whole phone set to 'silent' and also I turned the volume down. It still plays when I start it up. It is VERY annoying that I have to go to another romm just to start up my phone in the morning so I don't wake everyone up.