Change an ellipse/circle's size from the center after it has been drawn

I've drawn several vector circles (all on different shape layers) in Photoshop and now would like to change their size to make them a bit smaller. Is there a way to do this and have them shrink/grow from the center?

If I select the layer then select the ellipse shape tool I can adjust the size from the tool options but that doesn't make the shape grow/shrink from the center.