remove _method param from rest params

framework/web/Request.php

@@ -283,6 +283,7 @@ class Request extends \yii\base\Request
 			$contentType = $this->getContentType();
 			if (isset($_POST[$this->restVar])) {
 				$this->_restParams = $_POST;
+				unset($this->_restParams[$this->restVar]);
 			} elseif (isset($this->parsers[$contentType])) {
 				$parser = Yii::createObject($this->parsers[$contentType]);
 				if (!($parser instanceof RequestParserInterface)) {