I'm receiving mail in my yahoo alert of information that i don 't care for. How can I stop that?

Delete the alert entirely: There are two ways to do this:

You can click the "Click here to unsubscribe" link at the bottom of the alert you have received. If you don't see the unsubscribe link, there should be a URL you can copy and paste in your browser address bar that will lead you to a site where you can unsubscribe. Follow the instructions.

Or, go to Yahoo! Alerts and sign in to the account you used to set up the alert. Click the "My Alerts" tab at the top of the page. Click the garbage can icon to the right of the alert you wish to delete. You will be asked to confirm that you want to delete the alert. Click "Yes" to delete.

Mark the address and email as spam and it will block more incoming email from the same sender.