title: How to remove a list of columns from pydatatable dataframe?
body: <p>I have a datatable Frame created as:</p>
  
  <pre><code>comidas_gen_dt = dt.Frame({
      'country':list('ABCDE'),
      'id':[1,2,3,4,5],
      'egg':[10,20,30,5,40],
      'veg':[30,40,10,3,5],
      'fork':[5,10,2,1,9],
      'beef':[90,50,20,None,4]})
  </code></pre>
  
  <p>I have created a custom function to select a list of required columns from a frame <code>DT</code> as,</p>
  
  <pre><code>def pydt_select_cols(DT, *rmcols):
      return DT[:, *dt_cols]
  </code></pre>
  
  <p>So, here is the recommend syntax to remove columns from DT:</p>
  
  <pre><code>DT[:, f[:].remove([f.a, f.b, f.c])
  </code></pre>
  
  <p>following the above syntax of DT, I've create another custom function to keep a side a list of columns as</p>
  
  <pre><code>def pydt_remove_cols(DT, *rmcols):
      dt_cols = [*rmcols]
      return DT[:, f[:].remove(dt_cols)]
  </code></pre>
  
  <p>I'm executing the function as</p>
  
  <pre class="lang-py prettyprint-override"><code>pydt_remove_cols(comidas_gen_dt, 'id', 'country', 'egg')
  </code></pre>
  
  <p>and it's throwing the error</p>
  
  <blockquote>
    <p>TypeError: Computed columns cannot be used in <code>.remove()</code></p>
  </blockquote>
  
  <p>Could you please help me how to go ahead with it?</p>