If you no longer want a specific stakepool listed in your Discord, you can use /configure-stakepool remove to remove it. You only need to provide the pool ID.
You cannot remove pools from your list if they are currently used by any delegation roles (can be listed via /configure-delegatorroles list)
The Bech32 (pool1…) or hex-based ID of the stakepool you want to remove. You can use /configure-stakepool list to get a list of pool IDs you can remove from your server.