のをやめました

stopped doing

→ の
phrase Rare #33,159
stopped doing Follows a verb in its dictionary form. The の nominalizes the verb, and をやめました means stopped or quit doing it. Polite past form.
JA: 私は毎朝コーヒーを飲むのをやめました。
EN: I stopped drinking coffee every morning.

トムフェイスブックを使うのをやめました

Tom stopped using Facebook.

トム薬を飲むのをやめました

Tom stopped taking his medicine.

トニー彼女の声を聞いてピアノを弾くのをやめました

Tony heard her voice and stopped playing the piano.