It looks like there are some modifications in your header.php file. You can try to replace it with default unmodified header.php file (please make a full site backup first), but be careful, there potentially might be modifications that you don’t want to lose.
Please remember about importance of regular full site backups (files and database):
Also you might want to check this tutorial:
As a workaround, you can try to use the following CSS code in order to make that text color the same as header background color, so it will be invisible, but it will still be there.
You can add CSS code in Dashboard → Appearance → Customize → Additional CSS (WordPress 4.7 and up).
Kind Regards, Roman.