title: Automatically delete rows with a date of -30 days with an onOpen() function
body: <p>I have a shared sheet with quite a few remote users, the sheet is a stock sheet for recording best before dates of products.</p>
  
  <p>I have about 50 entries a day that go 'out of date' but would like to keep a months worth of records.</p>
  
  <p>Does anyone know of a script that would delete any rows with a date in column C of today -30 which works with an onOpen function?</p>
  
  <p>I have found several that work but i need one that works onOpen.</p>