function truncate(recno : Integer): Boolean;

The function truncate(N) removes all records after N.
This operation cannot be undone.

begin
    // your code
    writeln( 'Reccount = ' + intToStr( dbf.recCount ) );
    dbf.truncate(100);
    writeln( 'Reccount = ' + intToStr( dbf.recCount ) );
    // your code
end;