Creo que puedes hacer:
Código (bash) [Seleccionar]
find /home/ftp -type d -size +150M -exec rm {} \;
Código [Seleccionar]
-type c
File is of type c:
b block (buffered) special
c character (unbuffered) special
d directory
p named pipe (FIFO)
f regular file
l symbolic link; this is never true if the -L option or
the -follow option is in effect, unless the symbolic
link is broken. If you want to search for symbolic
links when -L is in effect, use -xtype.
s socket
D door (Solaris)