- (BOOL) truncate:(NSInteger) recno;

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

{
    // your code
    NSLog( @"Reccount = %ld", [dbf recCount] );
    [dbf truncate:100];
    NSLog( @"Reccount = %ld", [dbf recCount] );
    // your code
}