If all you're trying to do is delete all parentheses from a line, you can use a character class (perlre):

use warnings;
use strict;

while (<DATA>) {
    s/[()]//g;
    print;
}

__DATA__
PP: (899040) Jane Smith
[download]

prints:

PP: 899040 Jane Smith
[download]

Update: similarly, you can use tr:

    tr/()//d;
[download]