Itunes run whenever the windows start, how to block no run?
A third party application is likely starting iTunes.  (such as plex media server)

Beginning with iTunes 12.2 the Library.XML file is no longer automatically generated. Enabling preferences > advanced > "share iTunes library xml with other applications" seems to solve the problem of some third party applications starting iTunes.  Apparently if the XML file is not present then the 3rd party application opens iTunes to access the library, if the XML is present there is no need to open iTunes.

Apple didn't explain this change well, and in fact the option isn't even included in the iTunes help file yet (at least windows iTunes help). Instead Google "share iTunes library xml with other applications" to learn more.