Caltech just did the same thing. They say “As of July 2018, Caltech no longer requires the SAT Essay or ACT Writing exam sections. Additionally, these sections will not be considered in the application review process.”
The following Higher Education articles says “Only 22 colleges appear to still require the writing test.”
https://www.insidehighered.com/quicktakes/2018/07/11/caltech-drops-satact-writing-test
I think this was largely caused by ACT’s rescoring irregularities when they temporarily went to a 36-point essay. Students who requested rescoring essays showed that there’s a large error bar in essay scoring.