title: Remove all unused rows and columns from Google Sheet
body: <p>Is there a simple way to remove all unused  columns and rows form a Sheet using GAS?</p>
  
  <p>If I use <code>sheet.getLastColumn</code> it only grabs columns with data, which makes sense but I think the Sheet looks cleaner if unused columns and rows are removed.</p>
  
  <p>I can remove them using <code>sheet.deleteRows(LastRow, x)</code> where x would be the number  of rows to remove after the last row with data, but that number isn't constant each time the script runs.</p>