When you have entered a value into a form, Firefox will remember it and suggest it the next time you use the form. When such a value is incorrect or for some other reason not relevant anymore you probably want to delete it. Very simple but not very well documented. Here is how it is done:
- Put the cursor in the field that the value is associated with.
- Press the down-arrow to show the drop-down the list of values and select the unwanted one.
- Presh Shift+Delete or Ctrl+Delete.
- The value is gone.
Simple if you now how. A right click popup menu would have been more intuitive in my opinion.