shell find -delete -- how to avoid delete itself

Question

root
  -- level-1-folder-1-dynamic
  -- level-1-folder-2-dynamic-maybe-empty
  -- level-1-folder-3-dynamic
     -- level-2-folder-dynamic-need-to-be-deleted
     -- level-2-folder-dynamic-need-to-be-deleted
        -- file-1
        -- file-2

I want to use find command to delete all level-2-folders that created 30mins before, but I can't find all level-2 folders and delete them.
What I can do now is to find all the files and delete them, but the level-2-folders still remain
find root -type -f -cmin +30 -delete
And if I using find root -type -d -empty -delete, it will delete all the empty folders, including level-1 and root itself.

How can I delete all the level-2-folders?
Thanks

Answer 1

To delete only those empty directories that are level 2 or deeper, use -mindepth 2:

find root -mindepth 2 -type d -empty -delete