fix 插件系统退出其它界面还是显示灰色滤镜的问题

Author: zhaoyongqiang

iOS/APIExample/APIExample/Examples/Advanced/SimpleFilter/SimpleFilter.swift

@@ -127,11 +127,10 @@ class SimpleFilterMain: BaseViewController {
         if parent == nil {
             // leave channel when exiting the view
             if isJoined {
-                agoraKit.disableAudio()
-                agoraKit.disableVideo()
                 agoraKit.leaveChannel { (stats) -> Void in
                     LogUtils.log(message: "left channel, duration: \(stats.duration)", level: .info)
                 }
+                AgoraRtcEngineKit.destroy()
             }
         }
     }