title: Removing a row in a DataFrame when a or b or c is true
body: <p>I have a dataframe df that has five columns. The first column is named Phase and contains text. I would like to eliminate any rows in the dataframe where Phase is either 'xyz' or 'ab' or 'tlimit'</p>
  
  <p>I tried the following but it didn't work:</p>
  
  <pre><code>df=df[df.Phase != 'xyz' or 'ab' or 'tlimit']
  </code></pre>
  
  <p>I also tried:</p>
  
  <pre><code>df=df[df.Phase != 'xyz' or df.Phase!='ab' or df.Pase !='tlimit']
  </code></pre>