WARNING: This page is about a different car, the 2006 BMW 760i, 2005 BMW 760i, and 2004 BMW 760i. However, it is still accessible from the selected car via links, so may be relevant.
Unlock hook (1) with special tool 61 1 360 and slide plug housing downwards out of base.
Fig 1: Identifying Hook With Special Tool (61 1 360)