In case of doubt, here's the announcement on fsf.org: https://www.fsf.org/news/richard-m-stallman-resigns

Vice published info about this earlier [1], including the actual email chain [2]

[1] https://www.vice.com/en_us/article/9ke3ke/famed-computer-sci...

[2] https://assets.documentcloud.org/documents/6405929/091320191...