Log Out Of Locked Apple Id

See -> If your Apple ID is locked or disabled

If your Apple ID is locked or disabled - Apple Support (CA)

-> Get a verification code and sign in with two-factor authentication

Get a verification code and sign in with two-factor authentication - Apple Support

If you can’t sign in, reset your password, or receive verification codes, you can request account recovery to regain access to your account. Account recovery might take a few days or longer, depending on the specific account information you can provide to verify your identity.

and i dont have the receipt of the purchase because so many years have passed i only have the Box (including the serial number and the other information abt the iPhone)

May be you can check your mail box?

How to remove Activation Lock

How to remove Activation Lock – Apple Support (UK)

If you need help removing Activation Lock and have proof of purchase documentation, you can start an Activation Lock support request.

1. Go to iforgot.apple.com
2. Enter your Apple ID – usually the email address associated with your Apple account.
3. You may be asked to confirm the phone number associated with your account.
4. You will then get Reset Password notifications on your devices (we received one on our Mac and iPhone). Click Show on a Mac, or just tap on the notification on the iPhone. 
5. On the Mac you will be taken to System Preferences – click on Reset.
6. On the iPhone you’ll see “Use this phone to reset password” – click on Allow.
7. If you are using an iPhone you will need to confirm your trusted phone number (which may or may not be the one associated with that device). Once you have done this you will see the message that you have to continue on one of your other Apple devices – as long as you have one available tap on Done. If not, tap on Cannot access Apple devices and you’ll be asked for a passcode that’s used for another device.
8. If you are using a Mac you will be asked for the Mac’s password. In System Preferences on a Mac, or on your iPhone, you will be asked to enter a new password.

Thanks.

[Link edited by Moderator]