how do i clear last years form data

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The form on my site is to enable people to enter their items in a competition. It is seasonal event therefore I would like to clear old data (2016) from the database to prevent adding last years data to this one.
I've removed the previous years data (2015) one entry at a time, which is very time consuming. I there a way to remove all the 2016 data by selecting all of it and deleting it as a group?