Acrobat reader add XMP metadata

Hi all,

I have notice that in some cases acrobat reader appending my pdf files the following:

<</Length 2916/Subtype/XML/Type/Metadata>>stream
<?xpacket begin="" id="W5M0MpCehiHzreSzNTczkc9d"?>
<x:xmpmeta xmlns:x="adobe:ns:meta/" x:xmptk="Adobe XMP Core 5.6-c015 84.159810, 2016/09/10-02:41:30        ">
   <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
      <rdf:Description rdf:about=""
            xmlns:xmp="http://ns.adobe.com/xap/1.0/"
            xmlns:xmpMM="http://ns.adobe.com/xap/1.0/mm/"
            xmlns:dc="http://purl.org/dc/elements/1.1/">
         <xmp:ModifyDate>2017-12-17T16:48:48+03:00</xmp:ModifyDate>
         <xmp:CreateDate>2017-12-17T16:49:45+02:00</xmp:CreateDate>
         <xmpMM:DocumentID>uuid:b1351a35-20e4-4671-82b4-c682feff801e</xmpMM:DocumentID>
         <xmpMM:InstanceID>uuid:d651a6c6-b9ea-4f9b-97ad-deb9cb37960e</xmpMM:InstanceID>
         <dc:format>application/pdf</dc:format>
      </rdf:Description>
   </rdf:RDF>
</x:xmpmeta>
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                                                                                                    
                           
<?xpacket end="w"?>

Why Adobe reader do this and how can i prevent him from doing it?

Thanks!