In the web UI, in clusters page, you can select multiple clusters and perform desired action on it. One action is Destroy clusters.

When you select Destroy clusters, the clusters, which cannot be destroyed (like attached to ACM, not created) are only detached. But there is not clear info about this action for this cluster and this should make confusion for users. It will be a nice to add info what exactly will be performed on each selected cluster like another column on list of selected clusters with text like "Cluster will be DESTROYED" or "Cluster can be DETACHED only"