"扭身脱掉衣服" can be translated into English as "twist one's body to take off the clothes" or more naturally, "turn around and take off one's clothes" (though "turn around" might not fully capture the "twisting" motion, it's a common and understandable expression). If you want to emphasize the twisting motion more precisely, you could say something like "contort one's body to remove the clothes" or "twist one's torso to take off the garment," but these might sound a bit more formal or literary.
For everyday conversation, "turn around and take off one's clothes" would be perfectly acceptable and easily understood.