Disconnecting your Libre data from Quin can be done through your LibreLink app.
To disconnect, open your LibreLink and tap the menu in the top left. From here, select "connect apps" and then "manage" on your LibreView app.
You should see "Terra" in the list which you can select to disconnect. Repeat this step for the LibreLinkUp app.
Please be aware that your blood sugar data will no longer be fed into Quin and you will need to enter manual readings or reconnect your Libre in order to get full use out of some of the features including the blood sugar graph and patterns.