How do I stop Turbo Tax from updating State tax forms that I no longer use?

You are not able to stop the update.  It is important to let the updates run as they could affect other forms or calculations. Updates are necessary to ensure an accurate return.

This is ridiculous!  When can this get fixed?  I used MA once a few years ago and now it automatically downloads and waste time updating every year since then.  Not to mention space taken on my laptop.

Can this be fixed soon?

No, as this is not a TurboTax program issue. The module for MA (I am a RI resident so I feel your pain) does not accept removal as it cannot read whether or not you've owned rental property in MA and have not transferred your current resident state in any future years. There is also the MA issue of changing their identity tools. My true sympathy to you in that annoyance as I have dealt with this as well.