I am considering deleting my account in chinese.stachexchange.com (but not other Stackexchange accounts) --- not now, but perhaps in the near future. In math.stachexchange.com, we only need to add the sentence "please delete me" in our profiles to notify the mods/admins for our requests, but I don't see any way to delete an account on this site.
Go to the bottom of any page on the Chinese SE site.
There should be a "contact us" option.
There should be an account deletion request option, and only your account on this site will be deleted. (If you want, you can specify that on the "additional comments" (or something similar) box if you want to be extra sure.)
I believe there were also instructions to replace the text in your "about me" box with "please delete this account", but if I remember correctly (from my experience with quitting some sites that didn't interest me enough) that's not the "main" step.