Hi @rachelkoh
Here's an image of the control board for the fryer that shows the location of the speaker - designated ''BUZ1'' (buzzer).
You could remove (unsolder) it from the board but then you would get no audible indication when the cooking time has been completed or when it has reached the desired temperature when pre-heating it.
Alternatively you could tape over the hole in the top of the buzzer (see enlarged image) to muffle the sound but I don't know how long the tape would stay in position as it is in a hot environment and may lift off.
Unfortunately I cannot find a video that shows how to disassemble the fryer so that you can gain access to the control board.
[image|3324807]
(click on image)