If I have a seat assignment on a Jetblue flight, is there a way to remove my seat assignment, so I'm confirmed on the flight but have no seat assignment?

The reason why I'd want to do this: I have a travel agency who bought a ticket for me and auto-assigned me a seat. I'd rather have no seat assignment and take my chances at the airport (who knows, maybe I'll get put in EMS; and in any case it won't be worse than the seat assignment I have no).

Is it possible to get there from here? Or is the only way to end up with no seat assignment to buy a ticket from jetblue.com and never select a seat in the first place?