I had this situation that I once logged into somebody else’s paypal account (with permission, mind you) and since then this this login email address was apparently permanently burned into the login screen.
I just could not get rid of it and it became very annoying because I had to select it first before I could type the first letter of the my own email for firefox to allow me to select the right one from a list. Before that I did not have to do the selecting – just type that first letter.
Today – finally – I had enough and went on a goose chase. The things I had learned to make firefox forget remembered form entries – Shift Delete, or was it Shift Backspace – did not do anything good.
I wasn’t sure if it wasn’t a cookie kicking in so I deleted all paypal cookies – no go!
To make a long search short – here is what I found: The file signon2.txt in the profile. There were data blocks starting with a period and I got rid of all those blocks that had paypal in it – and that pesky login email. Also got rid of all the paypal URLs at the top of this file and – voila – pesky entry gone.
Hope this helps somebody.