If you see an alert with a Request Access button, you might be able to request access to your account by tapping Request Access. If that does not work, this link —> https://getsupport.apple.com/?PGF=PGF63005&category_id=SC0245&symptom_id=23626 is the most direct way (versus Contact - Official Apple Support ) to get to the people helping you with this,
or by telephone at one of the numbers in this support article --> Contact Apple Support - Apple Support
If you have not used the account in a long time, note:
Legal - iCloud - Apple
VII. B "In addition, Apple may terminate your Account upon 30 days’ prior notice via email to the address associated with your Account if (a) your Account has been inactive for one (1) year"
I am taking "Verification failed" to mean you have tried unlocking the account but you cannot provide Apple with sufficient proof that you are the true account owner. If A person at Apple cannot help you, simply deleting the account (which requires you be able to get access to the account anyway) won't help if you are signed into a device with it. It will just render the device completely unusable. In that case, to get a device working again you will have to hope you kept your receipt and can ask Apple to reset it. Apple can completely reset a device if a person can provide sufficient evidence of valid ownership. Read the requirements and steps for an Activation Lock support request at: https://al-support.apple.com/#/additional-support Apple says you need to have "proof of purchase documentation” and “proof of ownership documentation”, but does not detail what currently constitutes proof other than it “must include the product serial number, IMEI or MEID.” User reports on this community indicate that typically Apple will ONLY accept an original receipt issued by Apple or an Apple Authorized Reseller. Presumably this is the only kind Apple can authenticate against fraud since Apple is not involved in third party sales. Apple recommends that you "Keep your receipt after you buy an Apple device" --> Keep your receipt after you buy an Apple device - Apple Support