If there is a surface to delete (such as a temporary cap), you can do so just by clicking it.
IMPORTANT
When using this tool, curves and surfaces may be difficult to see because the dental prosthesis and other visible layers are enabled. If this tool is enabled, selecting the tool a second or third time switches specific visible layers on/off.
Selecting the tool a second time displays only curves.
Selecting the tool a third time displays only surfaces and curves.