Just be careful about "deleting" your Yahoo account.
> Register a previously used ID
> A deleted Yahoo account ID may become available for future use, and you’re welcome to try to register it. However, Yahoo can't specify how long until a deleted ID may become available, and we can't guarantee that it will become available.
And make sure it doesn't get removed for inactivity:
> If you rarely use your account, it will go into an inactive state and then be deleted. You can prevent this by signing in to your account using any device at least once every 12 months.
I came here to say this. You probably don't have old, forgotten accounts laying around with your Yahoo email address tied to them, but if you do, Yahoo reserves the right to hand over your password reset abilities to the next person who wants your username.
DON'T DELETE YOUR YAHOO ACCOUNT. Purge it of all content, sure, but flat-out deleting it is very risky.
Almost all commercial mails, including newsletters, past orders, discount offers based on purchases, etc., use an "unmonitored mailbox" or an invalid address to send information. Any reply, manual or automatic, will never get seen by anyone on the other side to take any sort of action.
The only way out is to trawl through one's account, hoping that at least one mail from each contact is available, and then changing the email address with each of those. For personal contacts, this would involve emailing them and hoping they see it. For commercial contacts, it would involve going to the respective site and figuring out how to change the address and confirm the new address. Overall, this would be a cumbersome process for many people.
> Register a previously used ID
> A deleted Yahoo account ID may become available for future use, and you’re welcome to try to register it. However, Yahoo can't specify how long until a deleted ID may become available, and we can't guarantee that it will become available.
https://help.yahoo.com/kb/SLN3060.html
And make sure it doesn't get removed for inactivity:
> If you rarely use your account, it will go into an inactive state and then be deleted. You can prevent this by signing in to your account using any device at least once every 12 months.