Deleting older TurboTax installations

I know this has been asked before, but I'm not getting the warm fuzzy I'm looking for. 

I have 6 older versions of TurboTax on my Mac. I was about to delete them when I wondered: how do I amend prior returns? Can I delete these old versions and still access the installers from Intuit if I had to amend a return? 

I have saved all my returns & worksheets as PDFs, but what if I had to amend a return? Do I have to keep older versions installed just in case?

 

Thanks!