Is it possible to update the itunes without updating Xcode?
If you have both iTunes and Xcode installed, Xcode needs to be closed to update iTunes even if Xcode itself is not getting updated. There are some dependencies between iTunes and Xcode for app provisioning and such and closing Xcode ensures that the installation will run through.

All that you need to do it quit iTunes and Xcode to make the update continue. Xcode will not get updated from the Store by that. 

By the way, if you're not a developer, consider to remove Xcode from your Mac to save space and hassles.