This applies to the BigCommerce Plugin.
To install the plugin, three pieces of code need to be added to your BigCommerce site template but different themes require different solutions. If installed via the BigCommerce app store, there is an interactive guide to walk you through the steps. Alternatively identify your chosen theme and work through the steps detailed in the article BigCommerce Plugin.
Uninstalling the Feefo plugin is detailed at the bottom of BigCommerce Plugin - Uninstall.