I began with Turbo Tax Online but was directed that I needed to upgrade to the offline version. I did so and completed my taxes. How do I get rid of the online version

[xmasbaby0]

You do not have to "get rid" of online.   You can just clear out any data you entered if you did not register, play or e-file, or you can just abandon the account.  Nothing will happen to it.  No one else has access to your account.

CLEAR AND START OVER. (Or...just clear it and do NOT start over...)

https://ttlc.intuit.com/questions/2586254-how-do-i-clear-and-start-over