Your Piktochart-created visual is your own creation, so it isn't possible to transfer your visual to someone else's account to edit. Each account is secure and for the use of the person who registers the account only. You can enjoy sharing by sending a Piktocard, or the URL once you Publish your visual. You can also send someone your finished visual as a jpg, png or pdf file you save upon downloading.
Please note that additionally, you can't edit in anyone's account, and the password is for one person only. We wouldn't want just anyone to log in and delete or change your hard work. Passwords should always be kept safe.