How to delete a single cached username from Chrome?
Go to Options → Personal Stuff → Manage Saved Passwords, hover over what you want to delete, and then click the x.
UPDATE (credits to camster342): It's now in Settings -> Show Advanced Settings... and Manage Passwords is the second link under the Passwords and Forms section.
If the data you want to delete is not a password but rather a saved form follow this:
When you type in a form field, a menu may appear, containing past text that you've typed in the field. To delete a specific piece of saved text, select it in the menu using the arrows on your keyboard, then press Shift+Delete.
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On Mac OS it's Fn+Backspace or Fn+Shift+Delete.
It is possible to delete the single or all the username from the Google user-box. Simply select the require username by keyboard arrows. Then use Shift+Delete.
- Open a web page in which a data field showing the problematic value appears
- Double-click the field to make it show its drop down
- Highlight the problematic value with your mouse
- Press Shift+Delete
The value disappears and won't bother you again.