How to delete apple ID and replace it with my new one even though my main one is locked

If you are locked out of your old Apple ID account, it cannot be deleted. The account holder is the only one that can delete the account and must be signed into the account to do so. See: How to delete your Apple ID account - Apple Support.

If you regain access to the account you can delete it. To reset the Password or to change the trusted number, if you're unable to receive two-factor verification, see: If you forgot your Apple ID password - Apple Support and How to use account recovery when you can’t reset your Apple ID password - Apple Support. If you have to start the account recovery process be prepared that it takes time. Usually its a few days, but can take up to a month. This all depends on the amount and types of data you have saved to your account that you can verify.

If you have a second account you're using and you want to change the email that is easy, but there are some requirements. The email you want to use cannot already be in use as an apple ID or as an alternate apple ID. So you can't use the email from the locked apple ID for instance. To change the Apple ID follow: Change your Apple ID - Apple Support.

Depending on exactly what you're trying to accomplish, in what way your main account is locked. whether you're trying to reuse the email, etc. these steps may or may not meet your need. The better you can describe how your issue is occuring the easier it is to point you to the correct resource.

If you're unsure of what is creating the issue and these articles don't help, then Contact Apple for support and service - Apple Support.