Updating my AssetStore products

Hi I have a question about updating the content i'm selling on the AssetStore.

I recently made a huge Update to one of my current products and basically renewed allot of code and moved everything into a new hierarchy inside the inspector (folder structure, thus changing all the locations the original scripts where referring to).

My question is. When my clients download their update trough the AssetStore, does the AssetStore delete their old version inside their project and install the new one? Or do they have to delete the old product manually before updating to the new one(different package same system, same results)?

regards