WARNING: This page is about a different car, the 2004 Audi A4, 2003 Audi A4, and 2002 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Removing Spacer Ring
Courtesy of VOLKSWAGEN UNITED STATES, INC.
A - Internal puller 18.5 to 23.5 mm, e.g. Kukko 21/3
If difficult to move, pull out spacer ring using multi-purpose tool VW 771.