How to do without NS prefixes in XPath query?

Question

JavaScript

I'm using the browser's window.DOMParser to parse an XML document

if (window.DOMParser) {
                xmlDoc = (new DOMParser()).parseFromString(xmlString, "application/xml");

Document with prefixes, here is an example:

<Debtor xsi:type="ns1:Individual" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
                  <ns1:PartyId>271229</ns1:PartyId>
                  <ns1:RegistrationAddress>
                     <ns1:City>Москва</ns1:City>
                     <ns1:Street>Зеленоград</ns1:Street>

Accordingly, I need to make a request
Debtor/ns1:RegistrationAddress/ns1:City
. With prefixes, the request passes normally.
How can I do without prefixes?
To successfully make such requests:
Debtor/RegistrationAddress/City
This is necessary because a document comes from the server in which the prefixes are constantly changing.