I haven't done any reading into this but as far as I know on the used Thinkpad I have Computrace is "available" but hasn't been connected to any sort of third-party tracking service.
Should I disable this forever? Is Computrace tracking me even with the service not connected to anything?
The main concern here is not "Computrace is tracking you", but "Computrace may be exploited". Basically, if Computraced is activated, it will actively attempt to inject its payload into Windows via BIOS to achieve persistence even after an OS reinstallation - like a rootkit. If a vulnerability allows an attacker to somehow control this process, nobody knows how far the attacker can go...
* Deactivate the Rootkit: Attacks on BIOS anti-theft
technologies
Should I disable this forever? Is Computrace tracking me even with the service not connected to anything?