... I have tried this using

perl -pe's/\x08//g' <20150625163139.xml >20150625163139.xml

But this gives error: Bad name after g' at <script_name>.pl line 13.

How are you invoking the above command? A Perl command invoked from the OS command line via the  -e switch should have a "script name" of "-e" and exactly one line. (Well, one line in Windows, anyway — what is your OS?) Also, you are still redirecting I/O to and from the same file at the same time, and this is still a bad idea (see hippo's previous reply).

An error message like "Code point \u0016 is not a valid character ..." suggests a source file character encoding problem: what is the encoding of 20150625163139.xml? Proper specification of MODE in the
    open FILEHANDLE,MODE,EXPR;
command (see open) should insure proper reading of any Unicode encoding from its file, but I have no idea if XML::Writer handles Unicode strings properly.