GM used to screw the clip holding the wire to the steering column. The way to remove the clusters on column shift cars was to pull the dash trim panel, take out the screw holding this wire that pulls the needle when the column moves.

This is older styles, but it'* probably very similar. If you look at the column where the column and dash come together you should be able to find it/figure it out. If need be I can consult the FSM in a few hours.

I've only come across a clip stiyle fastening method for the indicator cable. It reminds me of the same clip that is used to fasten connectors to thin pieces of metal or plastic. These fastener types are found on the airbag connector under the dash and the flashers for example. They sometimes can be pulled off by hand but you might need a small flat blade screwdriver to pry off.

The cables should go halfway around the column and attach to the bottom. This allows for easy access for adjustment.