I deleted the Apple ID (gmail) 3 months back.
If you have deleted it, it is no longer valid, it simply no longer exists and it no longer works.
To understand about a deleted Apple ID, see the Apple articles below:
How to delete your Apple ID account
How to delete your Apple ID account – Apple Support (UK)
Understand and control the personal information that you store with Apple
Understand and control the personal information that you store with Apple - Apple Support
But whenever I log in ton appleid.apple.com and try to make the transfer
Your Apple ID is the personal account you use with all Apple products and services. It includes the email address and password you use to sign in, as well as the contact, payment, and security details that you use with Apple.
You can’t merge multiple Apple ID accounts.
For more support and assistance see -> Contact Apple for help with Apple ID account security
Contact Apple for help with Apple ID account security - Apple Support

Installing iOS beta version is at your own risk.
See --> How to uninstall iOS or iPadOS beta software
iOS 16 version has not been released to the public, so you have to wait.
We are not allowed to discuss about Beta version here.