Hi there!
Thanks for your query.
The copyright text removal from the footer is related to the Template but not with the SP Page Builder. If you are using the Helix framework, then you will find the copyright option within the Footer portion of the Basic tab. There are available within your Template Options.
Here is the related doc link:
https://www.joomshaper.com/documentation/helix-framework/helix-ultimate-2/basic#helix-footer
Note: Path towards copyright option: Extensions>Templates>Styles> Click on your current default template name then choose Template Options. Then find copyright of the Footer within the Basic tab.
Best Regards