The Sims Wiki:Report

Spam such as advertising links and vandalism is strictly prohibited on The Sims Wiki. If you see any, please report it to the administrators by using the Report a problem with this page at the bottom of each article. Alternatively you can contact an administrator.

You can also undo the edit someone made if it spamming or vandalism, but be sure to alert an administrator as well so we can send the user a warning or issue a temporary block if it is neccesary.