Compatible models: OLED65/77W9WNA, OLED65/77W8WNA, OLED65/77W7WNA
Try this
Are you seeking to turn off the startup and shutdown sounds?
➔ Change the [TV Power Sound] settings in TV Settings.
Changing TV Power On/Off Sounds
Press the

button on your TV remote, select [All Settings] → [Accessibility], and set [TV Power On/Off Sound] to On or Off.
① Turn on the TV and press the [Settings] button on your TV remote.
Select [All Settings] in the [Settings] menu.
② In [Additional Settings], set [TV Power On/Off Sound] to Off to disable the startup/shutdown sounds.
Note
You can only turn on/off the TV power on/off sound in the Additional Settings menu.
You must adjust the TV volume to change the power on/off sound volume.
This guide was created for all models, so the images or content may be different from your product.