Remove Subtasks from Outlook Calendar Sync

I currently use a separate project as a Marketing Content Calendar, where people in the company can view upcoming marketing activities (which are set as tasks with deadlines) in their Outlook Calendar.

The issue is the subtasks are syncing into the calendar view on Outlook, even though they are not assigned specifically to a project. The subtasks have deadlines assigned to them, they do not show up in the calendar view on Asana, but in my Outlook calendar it does. How can I remove the subtasks from Outlook for my team?