I remember hearing "be more chill" meaning, "calm down" in the nineties but it was not in common use ten years later - although "chill" as a verb with the same meaning lingers on. The expression "I'll school you" is long out of date, but when did it go out? Some expressions go out of style and then return, for example "fly" meaning "good looking" has been going in and out for centuries. Is there a site that tracks this kind of thing? How about a book?
Most serious slang dictionaries put considerably more effort into identifying when a term arose than in trying to identify when it fell out of widespread or well-informed use. In part this is because documenting usage generally involves finding published instances of it—and noting that published instances of a term have declined or vanished is not an altogether reliable way to determine whether and when usage declined in the wild.
Not only is the dictionary maker in the awkward position of making a judgment about oral usage patterns on the basis of a written record, but the written record may yield multiple instances of usage of a slang term after it is essentially moribund in the wild, either because the recent written work is an academic inquiry into past slang or because it is a book set in the past and using then-current slang. On top of all that, slang isn't predictable or stationary. A formerly hip term like dig may survive for decades despite being used only by the least sophisticated demographic groups in society, only to emerge again as a hip term many years later. In short, it's difficult and dangerous to declare a slang term dead—and identifying when the term ceased to be used by the most sophisticated elements in society is highly subjective and (again) exceedingly difficult to determine.
A couple of sources make a serious effort to identify both when a term emerged and when (if ever) it fell into disuse. On the UK side, Eric Partridge, A Dictionary of Slang and Unconventional English, which passed through at least eight editions during the twentieth century, makes a serious effort to track when terms dropped out of use as well as when they came into play; Partridge's dictionary emphasizes British slang because Partridge was British, but he tries to address U.S.slang as well.
Among U.S. books, I think that J. E. Lighter, Random House Historical Dictionary of American Slang (two volumes, 1994 & 1997) does the best job of noting when a slang term has fallen into "historical use only." Unfortunately, Lighter's dictionary takes you only through the letter O; I don't think that the P–Z volume was ever published. Other resources such as the Dictionary of American Slang (which has been through four editions, first from Crowell and then from Harper Collins), the Oxford Dictionary of Modern Slang, and of course the early and monumental Slang and Its Analogues (from the turn of the twentieth century) do a nice job of documenting first (and subsequent) occurrences of the various slang terms, by date; but they don't concern themselves much with the obsolescence of such terms.