You can get the Branding Free License Add-On for your Ultimate Web Builder software to remove the “Powered By UltimateWB” line on the footer of your website frontend.
If you have bought UltimateWB software, add it from the Branding Free License page: https://www.ultimatewb.com/branding-free-license
If you are on a Cloud plan, you can add it directly from that page: https://www.ultimatewb.com/cloud-website-builder
Please note this does not allow you to rebrand the UltimateWB software with another name, so it is not white label.
In any case, you can also add your own “Website Designed By” or “Copyright” lines to the footer as well – no add-on required.