Usernames are permanent and cannot be changed.
If you want a different username, you may open a new Photobucket account with a new email address. An email address can only be associated with a single Photobucket account.
Additionally, we are unable to transfer the content of one account to another. This can be completed by downloading the images from the old account, then uploading them to the new account.
You can create a new Photobucket account by clicking here.