Can't do that unless you've activated your account. Nor, mind you, would anyone have the time to do that for the possibly hundreds of threads they've participated in before.
Point is, please don't resurrect threads like this. This doesn't require a debate.
And, for those of us who transitioned from the mailing lists to Swift Forums, all previous threads we participated on (hundreds of them for some of us) are in Watching mode and Discourse has no easy way I have found to mute them all.