I've asked this too but never really got a time saving answer.  The one I remember was to go and delete each single morph individually.  I don't have the time nor patience to spend 3 hours deleting several dozen individual morphs so I've just left them.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi