How do I stop the activity showing on 'My Fitness Activity’ block on the dashboard?

You can disconnect Strava by logging into your Strava account, going to your profile, then finding your social Connections. You can then disconnect Coastrek from your Strava account.

You can disconnect Fitbit by logging into your app on your phone, go to settings, go to Third Party Apps, Manager 3rd Party Apps, and revoke access for Coastrek.

You can disconnect Garmin by opening the Garmin Connect app, access the menu by selecting More (bottom right), select Settings, select Connected Apps, under CONNECTED APPS choose Coastrek to be prompted to remove access, select Disconnect and finally acknowledge pop up message by selecting DISCONNECT.