A given years .tax20xx file can only be read by that years software. I keep the software for at least 7 years. Although in most circumstances you can only amend for a refund the last 3 years, the IRS can go back 7 years for missing income, so it is good to be able to access the actual data file for those years.
Unless you are short on storage, there is no reason to delete the application or Applications Support files for that year.
TurboTax 2010 runs fine on the latest Mac OS.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
