Just create a new web page. Place a link on the old one that redirects to the new one.
After about 6 months the info on the old one will fall to page 2 or 3 of a Google search.
Very few people - if any will see the old information
If you are referring to your own web page, this is correct.
If you are referring to the multitude of sites that compile business information, just change the original source -- i.e. your listing at the phone company, or your business registration with your state. The aggregation sites collect this published info, and it will eventually update them.
To speed up the process, you can go to each individual site and submit a correction. This is all that Yext is doing for you, and charging you for it.
He’s talking about internet “yellow page” listings, not his own website. Those are private databases and they may charge you for a listing or to change a listing.
However, I wouldn’t worry too much about it, if you put up your own website for your business and get it ranked properly in the search engines, then everyone will get your contact info straight from you and only idiots will bypass that to get the incorrect info from “yellow page” websites.