In SharePoint 2013, Lists and Subsites are added to the Quick Launch automatically. Is there anyway to stop this?
When you create a List it has an option whether to show that list in Quick Launch or not, you can uncheck the checkbox, as shown below:
If you are making the list via code, you have
SPList.OnQuickLaunch property, which you can set to false!
You can activate Publishing feature for your Site and once your Web is Publishing.. In Site Settings -> Under Look and Feel -> Navigation. There you can handle whether or not to show subsites and pages under Quick Launch/Top Navigation (Current Navigation)