You can add, delete, or rename your own folders. To do so, go to the folder list by tapping the "Menu" icon . Scroll down and tap the "Settings" icon  . Go to the "Folders" section.

To add a new folder, tap "Add Folder". Enter the folder name and tap "Add".

To delete a folder that you previously created, tap "Delete" next to the folder name. To rename a folder, tap the folder name. Enter the new name and tap "OK".

Please note that currently you can only edit the folder list for mailboxes in the my.com domain