Yes, you can disconnect your Starling app from your Zettle account at any time. To stop Zettle data being shared with Starling, log into your Zettle account on my.zettle.com, select Integrations, then Connected, and then the Starling Bank integration. Tap to open it and hit Disconnect.
To remove the Zettle tile from your Starling Marketplace, log into the Starling app and head to the Marketplace section.From there, tap on your Zettle tile and select Remove.