how to remove local package from asset store

I buy the 2dtoolkit package and download it to local. Then it has a new version, and I upgrade and download it. Well, the problem is when I create a new project, there is two 2dtoolkit package there and how can I delete the older version one.
Thanks~

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Exit Unity and browse to C:\Users\YOU\AppData\Roaming\Unity\Asset Store\ and remove whichever packages you no longer want.

I would suggest just moving them to another location for archival purposes instead of completely deleting them.