Same problem here. I can't remove the added folders. Not so cool

I have a mailbox hierarchy like the following:
- Inbox
- Customer 001
- Customer 002
- Customer 003
- Project 1
- Project 2
- Project 3
- Project 4
- Customer 004
- Drafts
- Sent
- Trash
- Spam
The best solution for me would be to tap the inbox folder to show the nested folders in a tree-like way. Maybe another solution could be to change the whole folder list to just show the nested folders and so on.
Since I work with those folders on a daily base, I really
need such a option.