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
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)