Changing email - says new email already in use

Hello - I opened my Digitial Reader acc using my work address at the time. I no longer work there so don’t have access to that email anymore. When I log in to change/update my primary email, it says the new email - my personal gmail - is already in use and won’t update.  Adobe Help Chat says my personal email is attributed to a non active subscription. How do I delete this non active account so I can update my Digital Reader to my personal email? Thank you.