We've all been been there, a channel gets closed, no-matter yet if it was a cooperative or force-closed, but somehow the close transaction hangs around and doesn't get confirmed. You want to clear the house, or need the pending onchain sats, but wonder how to go about it? Follow this guide and you'll hopefully find remedy.
But before, read this article from LND. Then read it again. Once you think you understand it, read it again. It's not super cohesive, since a number of things from the top need to be understood to grasp the section Channel closing, so ensure you spend some time in there.
This is written for LND, but similar methodologies are applicable for CLN. Eclair folks know their way around anyway. You identified a channel-close, either in one of the GUIs you use, or from a Bot notification. But it doesn't confirm. First thing to do is SSH into your node via ssh user@node-ip and get an overview of all pending (open, and close) with lncli pendingchannels.