title: Deleting rows satisfying certain conditions in R
body: <p>I have a table Y, comprising of 6 columns. (Date, hour, min , sec , price, size).
  So now i am supposed to delete entries which have time greater than 4 pm. the entire row of entries must be omitted. I am not quite sure how to proceed with this. So basically we will be looking at the hour column and making the comparison. 
  ex:</p>
  
  <pre><code>Date       hour min sec price size
  jan1st     9    45  45  345   100
  jan1st     10   23  33  324   20
  jan1st     11   02  34  434   10
  jan4th     16   05  09  32    23 
  jan5th     23   08  23  12    90
  </code></pre>
  
  <p>So in the above table, I would like to delete the entry that has 16 and 23 under the hours. and hence get rid of the entire row. How would i do that?</p>