Do I need to keep past years Turbo Tax programs on my computer so that I can complete this year's tax return?

I have Turbo Tax programs for every year since 2007 loaded on my computer.  That's taking up memory.  I know the current year tax program looks back to my tax information for past years.  Does it look back beyond the most recent past year.  I will be doing by 2016 income tax soon using Turbo Tax.  How many past years do I need on my computer to do the 2016 taxes.