I think it works more like a mute button and wasn't meant to delete posts.
The forum has a function in your Profile to add Buddy and Ignore Lists. I haven't seen much change with the Buddy function yet.
In contrast, the Mobile version (via Tapatalk) also has the function to Ignore only (nothing for Buddy Lists, though.)
In Tapatalk, you can select a poster's profile. At the top right, select the three dots.
Only the option to Ignore/Block will be visible.
Afterwards, in Tapatalk, the posts will show similar to the desktop version.
But adds a way to rehide the post after you read them.
Later, you can choose to Unignore/Unblock via Tapatalk as well.