My friend is facing a similar issue, he created an account with an email but later closed the account.
He is trying to sign up again with the same email and got this message: "This email address is associated with an inactive account. Contact Upwork Support if you want to use this email address or register with another email address."
In order to log in and have support, I am posting this on his behalf and found a thread from a person who faced the same issue and tries to PM Upwork Moderator 'Bojan S' but Access was denied. I got this message: "You do not have sufficient privileges for this resource or its parent to perform this action."
Any help will be appreciated, thank you.