dired-recursive-deletes

dired-recursive-deletes is a variable defined in `dired.el'.
Its value is

top

Documentation:
Whether Dired deletes directories recursively.
If nil, Dired will not delete non-empty directories.
`always' means to delete non-empty directories recursively,
without asking. This is dangerous!
`top' means to ask for each top-level directory specified by the
Dired deletion command, and delete its subdirectories without
asking.
Any other value means to ask for each directory.

You can customize this variable.