If you choose Edit > Undo the last editor action performed is undone. Successive use of Edit > Undo revokes more actions (rather than undoing the last Undo command, as is the case with many other editors).
When using Emacs emulation you can undo via the Emacs keystroke
. Thus, to undo the last five words typed, press
If you are using KDE/Gnome editor emulation, press