Removal of rear spoiler:

WARNING: This page is about a different car, the 2002 BMW M Roadster, 2002 BMW M Coupe, 2001 BMW M Roadster, and 2001 BMW M Coupe. However, it is still accessible from the selected car via links, so may be relevant.

When cutting out the rear spoiler:

Wear protective goggles and protective gloves.
The adhesive bead is cut through with a heavy-duty scalpel, if possible without damage to the rear spoiler.

To remove residual adhesive bead from rear spoiler and from rear window (if rear spoiler is to be reused):
Use a scalpel for heavy-duty applications.