If you are using the free Basic version of Clover Online, you'll change your business name directly in your clover.com account.
To change your business name log into clover.com if you aren't already. Then from your admin panel, select the "setup" app.
Then, under business name, simply delete the old name and enter the new one.
After a minute or so, refresh your Clover Online browser and your new name will be reflected on your site.