You can remove selected clusters from the Details View. If you right click on the Details View listing of clusters, a Delete option shows up in the context menu. By clicking this option, you can remove the cluster from selection.

You can add clusters to a selection manually using the Add Clusters option in the context menu of graphics view. To make use of this option, select multiple edges or faces that form valid clusters from the graphics view. Right click to see the option Add Clusters in the context menu. The selected clusters are added to the Details View when you click on this option. Note that you cannot select edges or faces that are already in the cluster list.

You can also remove selected cluster(s) from the graphics view. To do this, select edges or faces of the cluster(s) to be removed. Right click in the graphics view. The option Remove Clusters will show in the context menu. If you click on Remove Clusters, all the clusters to which the selected edges or faces belong are removed from the cluster list. Note that if the selected edges or faces do not belong to any of the existing clusters, the option Remove Clusters will not be available in the context menu.