Hello Anthony.

You can manage your saved passwords by going into Tools > Options > Security > Passwords:Saved Passwords... Also, in Tools > Options > Security > Passwords:Exceptions... you can set Firefox not to ask you if you want to save a password on a given site.

I hope this is what you're asking.

Websites remembering you and automatically log you in is stored in a cookie: Tools > Options > Privacy > Cookies You can remove the Gmail cookie(s) to make the site forget you.

Make sure that you do not set a checkmark in box on the Gmail login page to remember you ("Stay signed in ").