Deleting cookies in Firefox (created with .Domain property)

[ShMiL]

Hi!
I create cookies with the .Domain property (because FF treats a cookie created in http://www.domain.com and http://domain.com as two DIFFERENT domains).

The problem is, I just can't find a way to set the expiry date of the cookie.
My guess is that I don't have 'permissions'...
I tried to change the expiry date from both www.domain.com and domain.com - and it didn't work.

Any idea for how to get rid of this cookie?

Thanks.