Right clicking on the left pane for menu item "Show Line Numbers" actually to hide them.
Or Window->Preferences->General->Editors->Text Editors
Untick "Show Line Numbers" & Apply works for the first time.
After opening a new file in Navigator or restarting CF Builder, I get line numbers back even the "Show Line Numbers" checkbox stays empty.
Seems it doesn't save its preferences properly. Annoying.
All CFB updates applied.
Running Windows 8.1