From: How to delete your Apple ID account - Apple Support
"What happens if I change my mind after I have requested that my account be deleted?
While your request is being processed, you can contact Apple Support [using this link --> Contact Apple for support and service - Apple Support ] with the unique alphanumeric access code you received, and we’ll help you cancel your request. After your account is deleted, Apple can't cancel the request, reopen your account, or restore your data."
If it is too late and you have a device still signed into it, Apple can reset a device if a person can provide sufficient evidence of valid ownership (usually the original receipt from Apple or an authorized retailer). Try this online here --> https://al-support.apple.com/#/additional-support (Yes, apparently this does work in this situation too: How to remove previously deleted apple id… - Apple Community )