Not sure why you're posting this on an XSLT forum.
If it's a one-off, find a text editor that will save the file in the format you want. If it needs to be automated, write a little program e.g. in Java that reads the file and writes out all but the first three octets to an output file.
Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference