$ perl -Mstrict -Mwarnings -E '
    my %args = (profile => "foo");
    my %ta = %args{qw{profile user password}};
    say "BEFORE:";
    say for keys %ta;
    delete @ta{grep !defined $ta{$_}, keys %ta};
    say "AFTER:";
    say for keys %ta;
'
BEFORE:
profile
password
user
AFTER:
profile