nullyfy の使い方

補足です:

「無効にする」に該当する英語の単語は色々ありますが、それぞれ使い方が異なりますので注意が必要です。

以下はGoogleでの検索結果:
"password disabled" About 248,000 results
"password revoked" About 3,770 results
"password invalidated" About 522 results
"password nullified" 5 results

He violated (or broke) the rules, so he had his card key disabled.

"he was nullified"とすると、「彼という人間が無効化された」という意味になると思います。

「カードキー」は"card key"でも"key card"でもどちらでもよろしいようで:
card key
noun
(especially North American English)
(also key card British and North American English)
​a special plastic card with information recorded on it that can be read by an electronic device, which can be used instead of a door key
https://www.oxfordlearnersdictionaries.com/us/definition/english/card-key