s/\x00+//g;

##</code><code>##

tr/\x00//d;   # a.k.a. "y///" : y/\x00//d;

##</code><code>##

perl -e 'print "foo\x00bar"  | xxd -g 1
# produces this output (note the null byte):
0000000: 66 6f 6f 00 62 61 72                             foo.bar

perl -e 'print "foo\x00bar"  | perl -pe 's/\x00+//g' | xxd -g 1
# produces this output (no null byte):
0000000: 66 6f 6f 62 61 72                                foobar