title: What is the best way to remove columns in pandas
body: <p>I am raising this question for my self learning. As far as I know, followings are the different methods to remove columns in pandas dataframe.</p>
  
  <p>Option - 1:</p>
  
  <pre><code>df=pd.DataFrame({'a':[1,2,3,4,5],'b':[6,7,8,9,10],'c':[11,12,13,14,15]})
  del df['a']
  </code></pre>
  
  <p>Option - 2:</p>
  
  <pre><code>df=pd.DataFrame({'a':[1,2,3,4,5],'b':[6,7,8,9,10],'c':[11,12,13,14,15]})
  df=df.drop('a',1)
  </code></pre>
  
  <p>Option - 3:</p>
  
  <pre><code>df=pd.DataFrame({'a':[1,2,3,4,5],'b':[6,7,8,9,10],'c':[11,12,13,14,15]})
  df=df[['b','c']]
  </code></pre>
  
  <ol>
  <li>What is the best approach among these? </li>
  <li>Any other approaches to achieve the same?</li>
  </ol>