11.9.2 Undoing commands

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 Ctrl+_ . Thus, to undo the last five words typed, press Ctrl+_ five times.

If you are using MS Windows emulation, press Ctrl+Z to undo.

Common LispWorks User Guide (Unix version) - 11 Apr 2005