Batteries for the main key with radio wave remote control, removing and installing: Removing

WARNING: This page does not describe the selected car, but rather 26 other vehicles, including the 2009 Volkswagen Jetta, 2008 Volkswagen Jetta, 2007 Volkswagen Jetta, 2006 Volkswagen Golf, and 2006 Volkswagen GTI. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Inserting Screwdriver In Slot Between Radio-Frequency Unit & Key (Non-Foldable Key)

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Insert a screwdriver in the slot between the transmitter unit -1- and the main key -2-.
Move the screwdriver in direction of arrow and unclip the transmitter unit from the main key.

Fig 2: Identifying Radio Frequency Unit Catches (Non-Foldable Key)

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Lever the transmitter unit apart on the two locating lugs (arrows).

Fig 3: Unclipping Upper Battery Out Of Holders Using A Screwdriver (Non-Foldable Key)

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Unclip upper battery -1- from the retainers -2- with a screwdriver in direction of arrow.

Fig 4: Identifying Battery Contact Plate (Non-Foldable Key)

Courtesy of VOLKSWAGEN UNITED STATES, INC.

The contact plate -1- has two straight edges. When these edges are turned towards the retainers the contact plate can be removed.
The contact plate can also be unclipped with a screwdriver.
Now unclip the lower battery from the retainers with a screwdriver.