Deleting unwanted code on home page

Check your wp-config.php file to see if WP_DEBUG is set to true. If so, change it to false.

There are a few things to consider:

• What version of PHP is currently running on your server?
• What plugins do you have installed?
• Try de-activating plugins to determine which one is providing the errors.
• Backup & update Plugins / WordPress core.

If you are a developer, you answer can be found here: https://stackoverflow.com/questions/10159990/converting-an-ereg-replace-to-preg-replace

Chances are that your version of PHP or plugins need to be updated.