I'm not sure of the question here. Are you asking if you deleted your data can you then recover it? Maybe depending upon how it was deleted and that you aren't using that drive as your primary drive (not booting from it and you haven't installed or added anything since the deletion.
If you are asking if you delete all of your data can someone else get at the data, the answer is yes. As the first response indicates there are ways of undeleting your data. If you simply delete files they are still there and you can search the Net for tools to recover. If you delete the partition you will have more difficulty in recovering but search for tools and perhaps you can get it back.
If a hacker wants the data and you don't use a tool to wipe the drive than if someone wants it bad enough deleting partitions and files is not enough.
Hope that helps. Please clarify as to 'permenently'.
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