In the texinfo manual of version 7.1 I can find the following about `@unmacro`:
You can undefine a macro FOO with ‘@unmacro FOO’. It is not an error to undefine a macro that is already undefined. For example: @unmacro foo However, this doesn't work. This input document ``` u.texi \input texinfo @unmacro foo @bye ``` processed with `texi2pdf` aborts: ``` ./u.texi:3: Macro foo not defined. @\unmacro ...se @errmessage {Macro #1 not defined} @fi l.3 @unmacro foo ``` Werner