title: Delete and completely remove the commit from git history
body: <p>I have a commits in my git history</p>
  
  <pre><code>1.commit 4930da17d8dd23d650ed38435d8b421816a0c451
    Date:   Sat Dec 5 14:34:18 2015 +0530
  
  2.commit e1ebbbb599ee20ebec3ca92c26266d9fd16e7ccc
    Date:   Sat Dec 5 13:22:20 2015 +0530
  
  3.commit 1c4a11a80eb054d24dafec2efed0b0282188e687
    Date:   Sat Dec 5 12:11:50 2015 +0530
  
  4.commit b4ab3c164a3a8d93e0a71a94b5c561cb5e20ebf6
    Date:   Sat Dec 5 12:09:56 2015 +0530
  
  5.commit 167b1d10258381f09663ce61fa88ce3bbcd404c4
    Date:   Sat Dec 5 12:09:21 2015 +0530
  
  6.commit c61bcadac673e1c83f4c14b66d56e23b12fa3198
    Date:   Sat Dec 5 12:07:58 2015 +0530
  </code></pre>
  
  <p>In that 3rd and 4th commit contains a wrong code, but unknowingly I committed and pushed.</p>
  
  <pre><code>3.commit 1c4a11a80eb054d24dafec2efed0b0282188e687
    Date:   Sat Dec 5 12:11:50 2015 +0530
  
  4.commit b4ab3c164a3a8d93e0a71a94b5c561cb5e20ebf6
    Date:   Sat Dec 5 12:09:56 2015 +0530
  </code></pre>
  
  <p>But 5th and 6th commits contains a correct code. I need this commit to work.</p>
  
  <pre><code>5.commit 167b1d10258381f09663ce61fa88ce3bbcd404c4
    Date:   Sat Dec 5 12:09:21 2015 +0530
  
  6.commit c61bcadac673e1c83f4c14b66d56e23b12fa3198
    Date:   Sat Dec 5 12:07:58 2015 +0530
  </code></pre>
  
  <p>Now I want to Delete and Remove completely whatever I changed in 3rd and 4th commit.</p>
  
  <p>I want delete 3rd and 4th commit from the git history. But not 5th and 6th.</p>
  
  <p>So that my branch will be safe.</p>