Under MyHome > MyIgnoreList enter the names of your stalkers one by one. They will then not be able to send you private messages or challenge you to a game. Visiting forums is optional so you can just stay away from where you've been in forum threads.
Simple thing is not to post anything you don't want anytone to read.
The only way you are likely to get the posts removed is to click the "Alert Moderator" option and explain your concerns. As you made the posts there should be no reason for them not to be removed.
If this fails your other option is to use the "Send Feedback" link at the bottom of the page, detailing your concerns, and hope that either Russ or Chris decide that the posts can be removed.