emacsclient - kill frame, not buffer

[Ken Goldman]

Coming from gnuclient, delete-frame would only delete the frame.

emacsclient seems to work differently.  delete-frame also deletes the
buffer that was specified when creating the frame.

Is there a command to get the gnuserv behavior - kill the frame but
leave the buffer open.

Why I want this:

As I edit many files, I may have 20-30 frames.  Eventually, I
want to kill some of those frames.  But I still want all the
open buffers.