When I had Progressive Auto Insurance I tried to cancel the policy online but was told by a representative in a chat session that it was not possible to cancel the auto insurance or any insurance with Progressive online.
The progressive insurance agent in the chat said I had to contact their customer service number and give them some information to confirm that it was me canceling the policy.
So unless they've changed things you'll have to call the progressive insurance customer service number and tell the customer service agent that you want to cancel the insurance policy with them.
They might try to get you to stay with them but if you really want to cancel your insurance policy with them then just keep telling them you want to cancel.
Also I was charged an early cancellation fee of around $60.00 I think it was since I canceled before my auto insurance policy was up.
They took it out of my refund and refunded me the leftover money.
The progressive insurance should be canceled immediately when speaking with a customer service rep.