WARNING: This page is about a different car, the 2003 BMW 525i, 2002 BMW 525i, and 2001 BMW 525i. However, it is still accessible from the selected car via links, so may be relevant.
64 1 020
Lever out license plate light (1) with special tool 64 1 020 as illustrated and remove.
Disconnect plug connection underneath.
Fig 1: Levering Out License Plate Light With Special Tool