Canceling scheduled Group Meeting Poll Meeting

To cancel a scheduled group meeting poll meeting, go to My Calendar, and find the meeting that you want to cancel. 

Click on the meeting to see more details. Click on Cancel Meeting.

You will get a dialog box asking your permission if you want to delete the meeting. Click yes. Your meeting will automatically be deleted. 
An automated meeting cancellation email will also be sent to the relevant invitees informing of the same.