To disconnect LinkU from your calendar, login to the Google account linked to your account, then visit this page:
You can remove LinkU's access to your Google Account by...
Make sure you’re signed in to your Google Account.
View the apps & services that have access to your Google Account.
https://myaccount.google.com/u/1/connectionsSelect the app or service whose access you want to remove.
Under “{App name} has some access to your Google Account,” select See details.
Select Remove access.