Focus stacking

[Afterimage]

I often have 15-20 photos to open as layers in PS to align & blend. The file size gets large. Can I delete all the PS layers below the top merged layer to reduce file size. I see no need for them. 

[dianer_macperson]

you might want to use them to create some channel masks first. or you can keep the layered file offline somewhere. I don't delete layers unless I'm sure I'll never need to move something around.

[Chuck Uebele]

I normally delete them, once the focus stack is done. Once in a while I need to tweak something and need the layer, as Dianer mentioned.