How do you delete a username from drop down menu on facebook login?

[simon]

I accidently put my username and password in the same space on my facebook login. Now when I go to log in, my username and password comes up in the drop down menu. I cant have it visible to everyone, so how do you delete it?? I've tried hovering my mouse over it and pressing delete and it doesnt work. Any ideas??
using chrome by the way

[Pihu]

when you next time open FB, before login press ctrl+shift+delete clear browser data begining of time.