Why are third-party apps installed on Android?

Question

Android

I have an Android tablet and the problem is that it automatically installs third-party applications, while making some of them system ones.
Here are the applications that are installed:

• Yeah
  
• lock screen with famous pictures
  
• 360 Protection
  
• Vold
  

And these applications have become system:

• Mp3 Free Download
  
• Super Video Download
  
• porn club
  
• love beauty
  
• Setting Provider
  

And others. Moreover, almost everyone has access to everything!

Answer 1

Some of the latest programs you downloaded. Downloads additional programs.

Answer 2

Why can't Vold be removed? Judging by the fact that it could become a system one, your device is rooted, so you can perfectly delete it, at least by killing the corresponding apk from / system / app /
Check if this application has been added to the device administrators - this may interfere with deletion