For example, someone who chooses to use a cd in a car, rather than connect their phone (even though their car has this option).
For further clarity, this isn't to do with technology constraints or computer literacy. Just a word for choosing and older piece of technology to do a task where there is new technology easily available. I hope this all make sense!
How does the adjective 'obsolete' differ from other similar words?
Some common synonyms of obsolete are ancient, antiquated, antique, archaic, old, and venerable. While all these words mean "having come into existence or use in the more or less distant past," obsolete may apply to something regarded as no longer acceptable or useful even though it is still in existence.
// a computer that makes earlier models obsolete
Where would 'antiquated' be a reasonable alternative to 'obsolete'?
While in some cases nearly identical to obsolete, antiquated implies being discredited or outmoded or otherwise inappropriate to the present time.
// antiquated teaching methods
When is 'archaic' a more appropriate choice than 'obsolete'?
In some situations, the words archaic and obsolete are roughly equivalent. However, archaic implies having the character or characteristics of a much earlier time.
// the play used archaic language to convey a sense of period
It depends on your precise meaning, and the intended audience.
It could mean ending:
Feature updates
Non-security bug fixes
Security fixes
Customer support / troubleshooting
Service, in the case of SaaS (software as a service)
Sometimes there will be different dates for ending each of these.
For a general-use single-word verb to mirror released, I suggest discontinued. That is, releases, support, etc. (whatever it is that you mean) are no longer continuing.
But I would prefer end of life, which though not a single word (unless you count end-of-life or EOL) is a common industry term, and usually denotes an end to updates or fixes. This is, for example, what the operating system Ubuntu uses: "Release date" and "End of life date".
Some other possibilities:
abandoned - implies the ending was unplanned
deactivated / defunct - accurate if the software is actually no longer functioning
decommissioned / retired - might work, though I would use this for when something actually stops being used, as when a particular company, user, or specific system is no longer using it
deprecated - describes software as replaced, or not officially recommended. This precedes its complete removal. This term is not widely used outside of software libraries (and software developers).
obsolete - not great, as it describes the need or use for the software, not the state of development or support; software can become practically obsolete long before any planned support date
sunsetted - a sunset is actually a period of time of limited support, so it doesn't fit a single date as you have requested. This term is frequently used, e.g. Google Reader
terminated - good, though if you didn't like killed, this might also be too strong
unsupported - good, though not all software is ever "supported" in the way some may think: regular bug fixes, support staff, etc.
Deprecated is often used to describe lower-level APIs/function/libraries that should not be used going forward. See wikipedia on software deprecation.