zahavasdad — I can think of a few Minhaghim that were practiced in earlier generations but not now. However, I am not certain if “abandoned” is the correct term.
Ma’amadot — selections from Mikra and Chazal read early every morning (including Shabbos). Very few people I know of, read this now. They are printed in some earlier Siddurim.
Washing clothes — Virtually everyone I spoke to never heard of the prohibition of washing clothes on Friday, even though this a Takanas Ezra (HaSofer). Some poskim maintain that the Takana is still in force today, despite automatic washing machines and non-Jewish nannies doing it, though there appear to be heterim; children’s clothes, etc…
Tallis & Tefillin — We don’t put these on during Mincha, even though the Ariza”l was careful to do this. I’ve seen Tshuvos HaGeonim about when to take them off at Maariv (when Maariv is said before Shkia, summer time).