I was doing some research regarding the possibility of deleting a post, and found this thread which was made back in 2013. The official response by Spotify was this-
"Hey folks we've come back to update this idea status as 'case closed'.
We are currently in the process of deprecating the Inbox/Messages feature within the Spotify app.
Extensive data analysis has shown that this feature has very low engagement. The huge disparity between the use of the feature and the manpower required to maintain it doesn’t merit keeping it running, so we've taken the difficult decision to remove it.
It’s still very easy to share and chat about music from Spotify. You can check out this support article to discover other ways for getting social. Thanks for your continued feedback everyone."
Here we are six years later, with an expotential growth within the community. Being able to have this option re-instated would be greatly beneficial for all users across the platform.
Updated on 2019-07-30
The thread you are quoting refers to the inbox functionality that existed in Spotify a while ago, which is no longer present. The discussion regarding this is located here:
If you are interested in removing a thread of yours in the Community, you can ask a Mod or Rock Star, and they can happily remove it for you.
Hope it helps. 🙂