。
She called off the party.
Literal
She [topic-は] party [object-を] cancelled.
取りやめる is a compound verb 取る ('take') + 止める ('stop'), giving 'to call off, cancel, discontinue.' It's slightly more decisive and final than キャンセルする (the loanword), which is more common for transactional cancellations like reservations and orders. The compound has a faint sense of withdrawing or pulling back from a planned commitment — the 取り adds an active 'taking back' to the plain 'stop.' For events like parties, ceremonies, or trips, 取りやめる is the natural choice in formal-leaning Japanese.