Clearing cookies on close_session

[Aleksey]

Hi
is there any option to clean browser cookies/session after finishing work with marionette? I’m currently using marionette to log in my account on some site. But after I close firefox browser and open it again, I’m still logged in. I’ve tried to manipulate with cookies and set-cookies headers when I log in, but no luck. Also it would be great have ability to do not close browser, but just some kind of re-session marionette to start test again?
Probably marionette has some kind of private or incognito mode, when I close the session it cleans all the cookies?
Any advice is really appreciated.
Thanks in advance.