in regards to removing the trim for the
dash mounted factory cd-player,
from book one of the factory service manual:
this trim plate is held in by tab retainers pushed into slots.
there are no screws; it is pryed out.
judicious use of a butter-knife or a thin putty-knife might help get it started,
then pull it out with fingers. take care to not lose the inserts within the slots.
pushing open the cover over the cup holders might improve clearance.
.....................................................................................
it's possible you may need to remove the shifter trim plate.
image and instructions here:
https://i279.photobucket.com/albums/kk145/Lmckinley99/x_riviera_1997_shifter_trimplate.jpeg
Note:
if you intend to work on your 8th generation Riviera,
you absolutely must get the 2-volume Factory Service Manuals.
mine came from eBay, but they are getting scarce.
these cars are not intuitive, and they are not simple. the electronics are complicated.
irreplaceable pieces can be easily broken in a unguided attempt at disassembly.
to maintain and modify or improve these 1995-1999 Rivs, the most important tool
you can buy is a pair of factory manuals.