If you don’t want to see a thread in the forum, you can use the “mute” feature. It’s found at the bottom of every thread. Click the button and choose “Muted”. The thread will then disappear for you.
Here’s a screenshot:
You can also mute/hide threads by tag. Just go into your user settings page and look for the “mute” option. It’s under Preferences → Tags. You’ll also see a way to mute other users, if there are any users you don’t get along with.