The password to one of my email accounts has expired and needs to be changed. However, Mozilla has saved it in the "password" space on my login page for this email account, and I cannot clear it. I have been told that I must clear "Forms" from my browser. However, when I follow the directions on the Mozilla site for clearing parts of my history, "Forms and Searches" is prechecked and grayed out, so clicking on it produces nothing.

Is there a way to clear the saved password without clearing my entire history?