while (defined($_ = <DATA>)) {
    my (@array) = split(/,/, $_, 0);
    if ($array[-1] =~ /^\h*(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\./) {
        splice @array, -1;
    }
    print join(',', @array) . "\n";
}
__DATA__
$line = U.S. abc xyz , newyork, USA, Feb. 2-4
$line =pqr ffg , Long Beach, california, Sep. 12-14
$line = Hello , St. Louis, Missouri, Mar. 29-31
$line = hello, How are u