I think there should be an option to remove a thread from 'view your posts'.
In example, when I first joined I posted on some forum games and now they just clog up my posts .. I never post on them anymore.
The 'unmark' (or something of the sort) button could be at the bottom of the page or something, along with the 'bookmark/un-bookmark'/etc.
I think it'd be a convenient way to get rid of the threads you don't post anymore, they just take up space in your posts.
- Zeph