title: Deleting rows dynamically based on certain condition in R
body: <p><strong>Problem description:</strong></p>
  
  <p>From the below table, I would want to remove all the rows above the quarter value of 2014-Q3 i.e. rows 1,2
  Also note that this is a dynamic data-set. Which means when we move on to the next quarter i.e. 2016-Q3, I would want to remove all the rows above quarter value of 2014-Q4 automatically through a code without any manual intervention
  (and when we move to next qtr 2016-Q4, would want to remove all rows above 2015-Q1 and so on)</p>
  
  <p>I have a variable which captures the first quarter I would like to see in my final data-frame (in this case 2014-Q3) and this variable would change as we progress in the future</p>
  
  <pre>
            QTR                  Revenue
  1       2014-Q1                 456
  2       2014-Q2                 3113
  3       2014-Q3                 23
  4       2014-Q4                 173
  5       2015-Q1                 1670
  6       2015-Q2                 157
  7       2015-Q3                 115
  ..        ..                    ..
  10      2016-Q2                 232
  </pre>
  
  <p>How do I code this?</p>