I haven't looked at the W3C fork of our work, but in the actual HTML Standard (maintained at the WHATWG), menu was not completely removed---just the mostly-unimplemented context menu feature. We left menu as a semantic alternative to ol/ul for menu-like lists.
There's also the case of things like marquee, which are not removed, but just marked as obsolete and something that web developers must not use. (Which in practice means that conformance checkers like https://checker.html5.org/ are required to complain about them; it doens't mean there's some godlike web-developer-enforcement committee going around preventing you from writing code that uses marquee.) Their implementation requirements are still in the spec; see e.g. https://html.spec.whatwg.org/multipage/obsolete.html#the-mar... and https://html.spec.whatwg.org/multipage/rendering.html#the-ma.... (Same for frame/frameset, by the way.)