Q: How can I disable the Voice Control with iOS 7.1.2 on my iPhone 4, it has no Siri option. ??

Howdy Ahsanshareefi,

As I understand it you want to turn off Voice Control altogether. According to this article you will need to setup a passcode, then you should be able to do so:

Tips for using Voice Control with iPhone and iPod touch

If you want to turn off Voice Control

 

To turn off Voice Control, you need to set a passcode first—if you haven't already. Then go to Settings > Touch ID & Passcode > Voice Dial and turn off Voice Dial. Music Voice Control is always on.

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All the very best,

Sterling