First, let me say i understand the issue; something that seems lost on many replies.
For clarification, the OP wishes to simply remove ALL files that have been nested in directories and subdirectories of the 'music' directory by the music application to the root of the 'music' directory. For whatever reason, it is easier for the OP this way. It is not for me to judge.
next, the last reply is correct. I just thought i'd type up a n000b hand-held version of the simplest, non-CLI way i can think of completing the task. it involves opening one or two explorer windows, performing an advanced search, and drag/dropping the results to the final destination. Note, this is from XP Pro, but should be very similar in most flavors of windows.
1. open the music folder (the directory where you ultimately want all of your loose files to reside--My Documents/My Music most likely)
2. click the Start button (lower left of the screen) then Search -> for Files & Folders
3. in the left pane, choose the little green arrow pointing to 'all files and folders'
4. Use the 'look in' pulldown menu to select 'browse'; choose the 'My Music' directory inside 'My Documents'
5. leave the 'all or part of the file name' field blank
[post edited for clarity]
6. click search
7. that will show ALL files in the directory, including the directories. click the grey header named 'type' to sort the results.
8. with the results sorted, you can easily select all the music files by click-dragging a box around them without selecting the unwanted directories as well.
9. with the music files selected, click and drag them to the folder/directory you opened in step 1.
10. with all the files now in the root of the 'My Music' directory, click the 'type' column of the 'My Music' directory to easily select the empty folders.
11. drag them to the bin