Head over to Settings > Integrations
2. Uncheck the box next to "Sync Google Calendar" and select "Disable Google Calendar sync".
3. As a precaution - we ask you a second time if you really want to disable the sync :) If so, select "Yes, disable sync".
4. Once you've disabled the sync, you will then see the two options for google calendar show up again. Select the preferred calendar option and follow the steps to syncing.
Related article: Syncing Google calendar with Assembled