The next page, as usual, shows you the change you are about to make, and asks you to confirm that you are intending to do this. Once you move a domain into another account, the person with access to that account has control over it and the only way to move it back would be for them to do so. Since you have moved the domain outside of your control, you would not be able to move it back yourself so you will want to double check the spelling of the username and all details before you commit the change.