The word "撕掉" is formed by combining the verb "撕", meaning "to tear", with the resultative complement "掉", which indicates the completion or result of an action, here conveying the sense of "off" or "away". Together, they create a compound verb where "撕" denotes the act of tearing, and "掉" specifies that this action results in something being torn off or removed, thus giving the word its meaning of "to tear off".