Position the rear side of the device (the side with Ethernet connectors) so that it is facing you.

Lift up the left side of the metal plate and slowly flip it over the right edge of the device.

To prevent damage, do not lift the metal plate straight up or use force. As shown in the second picture, the fan is attached to the metal plate and connected to the logic board next to the power connector.

Since many people have had serious problems with the fan power connnector breaking, it is advisable to NOT try to disconnect the fan power connector. Be VERY careful with this connector. It is extremely fragile. If you absolutely have to disconnect the fan from the logic board, VERY carefully use a spudger or tweezers to do so.