How do I prevent lnd from participating in new channels? I have a lnd node that I would like to to cycle down completely. I would like to close all its channels and prevent that the node participates in any new channels while I'm waiting for the force-closed channels to mature.

What settings do I need to use in lnd to prevent my node from creating new channels, and to decline any new inbound channels?
You can set the option --maxpendingchannels=0 to disallow peers to open channels to your node.