"扭身脱掉衣服" can be translated into English as "twist one's body to take off clothes" or more naturally, "turn around and take off clothes" (depending on the context, if "扭身" specifically implies a turning motion).
A more contextually rich and idiomatic expression might be:
"Twist/Turn one's body and strip off (one's) clothes" (where "strip off" is a colloquial and slightly more vivid way to say "take off quickly or completely").
For a more straightforward and commonly used phrase in everyday conversation, "turn around and take off your clothes" would suffice.