There is an email that I cannot seem to dissociate from my Apple ID.

To recover your Apple ID, you can use:

 If you forgot your Apple ID  https://support.apple.com/en-us/HT201354

You also can use Having trouble signing in/iForgot https://iforgot.apple.com/password/verify/appleid

But, are you seeing activation lock? If yes, you can turn activation lock off only by entering the correct Apple ID/password combination. The correct combination is the one allowed by the person owning the device. If this combination cannot be entered, then the iPad is useless to you unless there are extenuating circumstances (e.g., you have the receipt for your purchase of the device with its serial number on it or a court order instructing Apple to assist in the provision of access to a decedent’s information from the deceased person's accounts--(see How to request access to a deceased family member's Apple accounts https://support.apple.com/en-us/HT208510) If you have either, contact Apple support using one of these options.

Get a call from Apple support to help solve your problem using this link https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362

Apple ID Support https://support.apple.com/apple-id

Apple ID account security for country-specific and region-specific help https://support.apple.com/en-us/HT204169

Get Support: We’re here to help  https://getsupport.apple.com/. Go through the options to find the best support option.

Is the email an alias of your Apple ID?

iCloud - Create or change email aliases. 

If so, you can't remove/change @iCloud.com, @me.com or @mac.com aliases.