Ketiva V’Chatima Tova. Can Hatarat Nedarim be performed at night? Thank you.
Yes, this is fine.
Hataras Nedarim does not have the full status of a Beis Din procedure, and therefore it can be done at night.
Rambam, Shevuos 6:5; Shulchan Aruch, Yoreh De’ah 228:3.
See Kol Nidrei Chap. 13 concerning using an even number of Dayanim, and Chap. 14 concerning a person who is disqualified from judging.