My document Named 'Myschool’structure is as below :

i am receiving an xml data from external system as below in my document named MYSCHOOL

When i use xmlStringToXMLNode and xmlNodeToDocument
i get the document as below :
Myschool
@version 1.0

100

Now how will exclude the @ field created from the xmlheaders and create the document in developer ?

You don’t need to exclude it. Just ignore it when mapping.

Or if you dont need the @ symbol but want something else then just map the particular string (for eg ATTR_) to the attrPrefix input field of the service pub.xml:xmlNodeToDocument.

In your case it will come as ATTR_version 1.0