I know that similar question was asked several times (for example: here, here,here and here) but it was for previous versions of Unity where the answer was dependent on used
There are only a few circumstances where Unity will dispose an instance. It is really unsupported. My solution was a custom extension to achieve this - http://www.neovolve.com/2010/06/18/unity-extension-for-disposing-build-trees-on-teardown/