How can I remove a hidden/ghost Google Calendar (Week Numbers)?

I'm currently cleaning up and consolidate my Google Calendar so as to simplify my life.

What I noticed is that Google has decommissioned the "Week Numbers" calendar which you normally would need to subscribe to. Instead, they turned this into a feature baked into the Calendar app itself. You can now go into settings to enable this feature.

Here's the problem:

My calendar apps, including outlook and Samsung Calendar, is telling me that I'm still subscribed to the "Week Numbers" Calendar! I want this gone because it shouldn't be there (I've tested this with a new google account, and this calendar is not there).

Below is an image of the Outlook client which has the Week Numbers calendar:

Below is an image of the Google Calendar Web App which does not have the Week Numbers calendar for me to unsubscribe from:

And below is the Google settings which does not have any option for me to unsubscribe from the Week Numbers calendar:

Here's how I've tried to fix this problem:

1. Going onto the Google web app, I couldn't see the subscription.
2. So I figured that I would reinstall my calendar clients on my desktop and mobile device. This did not fix the issue, I'm still left with a "Ghost Calendar" in my calendar client
3. Next, I reset my mobile to default settings and cleared content as if it is fresh. After reinitialising the account, I'm dumbfounded to see that the Calendar is still there!
4. Next, I initialised the account on a completely separate mobile device. Still same result. At this point, I figured it is something to do with my Google account. However, I cannot find anyway to access this ghost calendar to unsubscribe from it.

Has anyone encountered this problem before, and have any suggestions on what I should do? If not, how can I get in touch with Google so that they can fix this problem for me?

You could to directly remove it using the Google API:

1. List all your calendars to retrieve the 'calendarid' of the 'Week Numbers' calendar using the list API call (click on execute on the right side, it will ask to link to your google account and the full list should be displayed just below). The calendar id was 'p#[email protected]' in my case, it should be the same in yours;
2. Now delete this calendar using the Delete API call: Enter the id found in step 1 into field 'calendarId' on the right, then clic on execute. I had to execute this step about 2 or 3 times, because the first it was displaying some authorization error
3. Once done, display again the list of your calendars: the 'Week Numbers' should be missing.