you need to edit the service.bat file on the wildfly9 folder (scripts/service) and as the file suggests (if you open it) - you need to edit the name.
REM Author: Tom Fonteyne
REM
REM ==================================================================
REM If more then one service is needed, copy this file to another name
REM and use unique names for SHORTNAME, DISPLAYNAME, DESCRIPTION
REM ==================================================================
set SHORTNAME=Wildfly
set DISPLAYNAME="Wildfly"
set DESCRIPTION="Wildfly Application Server"
REM =======================================================
Hope that helps :)