I wrote \"exclude-result-prefixes\" and even then I see the name space occurrence appearance in output.
exclude-result-prefixes
just removes the xmlns:foo=""
attributes on the root tag of the result. The tags are still bound to the same namespace. Since the tags does not have any matching prefixes, the default namespace is used.
If you wish to remove the namespaces completely, you could use the following stylesheet:
(source: TEI wiki)