It is possible to use the unit without the fan. However, there would be some temperature concerns and this model does have a buzzer when the temperatures of the drives inside reaches a certain temperature.
The other option to consider is to purchase one of our newer versions of this product. The model that would take the same size and tray and have 5 drives bays would be the MB155SP-B (https://www.icydock.com/goods.php?id=155). The MB155SP-B uses a screw-in 80mm fan and allows you to use a different aftermarket lower-profile 80mm fan
If you have any questions on our products, feel free to send us a message.