How to read Excel file from C# code?

I am reading an Excel file in the following way and it works for me, but I always get this dialog that tells me if I want to save changes.

What can I do so that it does not appear?

C# code:

public List<Person> LeerArchivo(string pathArchivo , IEngineTool Tool)
        {
            Person p = new Person();
            List<Person> lp = new List<Person>();
            Excel.Application xlApp = new Excel.Application();
            Excel.Workbook xlWorkbook = xlApp.Workbooks.Open(pathArchivo);
            Excel._Worksheet xlWorksheet = xlWorkbook.Sheets[1];
            Excel.Range xlRange = xlWorksheet.UsedRange;
            int rowCount = xlRange.Rows.Count;
            int colCount = xlRange.Columns.Count;
            string strValue = string.Empty;

            for (int fila  = 2; fila <= rowCount; fila++)
            {
                for (int columna = 1; columna <= colCount; columna++)
                {
                    if (xlRange.Cells[fila, columna] != null && xlRange.Cells[fila, columna].Value != null)
                        strValue = strValue + xlRange.Cells[fila, columna].Value.ToString()  + "#" ;
                    else
                        strValue = strValue + "NO_DEFINIDO" + "#";
                }
                p=SetPerson(strValue);
                strValue = string.Empty;
            }

            GC.Collect();
            GC.WaitForPendingFinalizers();
            Marshal.ReleaseComObject(xlRange);
            Marshal.ReleaseComObject(xlWorksheet);
            xlWorkbook.Close();
            Marshal.ReleaseComObject(xlWorkbook);
            xlApp.Quit();
            Marshal.ReleaseComObject(xlApp);

            return lp;
        }

Dialog I need to remove: