So the thing is, you're not supposed to do that.
To close or "delete" an old Upwork account and begin using a new one is a violation of one of Upwork's most important rules.
You need to open a customer support ticket, apologize for your mistake, and ask them to help you close your new account and begin using your original account.
It is certain that someone has flagged this thread to bring this to the attention of a Forum Moderator.
So you are going to want to get on top of this as soon as possible.