diff --git a/runbooks/source/delete-cluster.html.md.erb b/runbooks/source/delete-cluster.html.md.erb
index 21179832..a2d5027f 100644
--- a/runbooks/source/delete-cluster.html.md.erb
+++ b/runbooks/source/delete-cluster.html.md.erb
@@ -24,7 +24,7 @@ In order to use this command, ensure you have the following installed:
 Execute the following command, providing the name of the cluster you wish to delete:
 
 ```
-cloud-platform pipeline delete-cluster --cluster-name <cluster-name>
+cloud-platform pipeline delete-cluster --cluster-name <cluster-name> --branch-name <branch-name-defaults-to-main>
 ```
 
 You'll be prompted to authenticate to Concourse: