There are many synonyms for the phrase "cut off his head," some of which are quite graphic and violent. These include "behead," "decapitate," "sever his head," and "strike off his head." However, there are also less violent alternatives that can convey the same meaning in a less gruesome way. For example, you could use the phrase "remove his head," or simply say "take off his head." While these synonyms may not be as impactful as the more violent options, they can still effectively convey the severity of the action being described. Ultimately, the choice of synonym will depend on the context and tone of the piece in which it is being used.