[LibreOffice] Delete entire row if text contains specific string

• Select a cell in Column M.
• Select all cells in the spreadsheet with Ctrl-A.
• Open the Data->Filter->Standard Filter menu.
• Set the first row of the filter so that Field Name is “Column M”, Condition is “Not Equals” and Value is “on”.
• Click OK to apply the filter to the spreadsheet.
• Select all rows in the spreadsheet with Ctrl-A. To unselect any column header cells, hold Ctrl and click the appropriate row.
• [Delete Row] Right-click on any of the row numbers and select Delete Rows.
  
  
  Reference:
• OpenOffice: Delete rows based on cell value