Remove separator line for only one cell

On iOS 8 you need to use:

cell.layoutMargins = UIEdgeInsetsZero

If you want to be compatible with iOS 7 as well you should do following:

if ([cell respondsToSelector:@selector(setSeparatorInset:)]) {
    [cell setSeparatorInset:UIEdgeInsetsZero];
}

if ([cell respondsToSelector:@selector(setLayoutMargins:)]) {
    [cell setLayoutMargins:UIEdgeInsetsZero];
}

ADD: If previous didn't work - use this. (from answer below)

 cell.separatorInset = UIEdgeInsetsMake(0, CGFLOAT_MAX, 0, 0);

If none of above worked, you can do:

self.tableView.separatorColor = [UIColor clearColor];

but this will leave 1 pixel empty space, not really removing a line, more making it transparent.

You can just visually hide separator through separatorInset property:

tableViewCell.separatorInset = UIEdgeInsets(top: 0, left: 10000, bottom: 0, right: 0)