There isn't a strike to remove. Here's how it works.
Step 1. Someone breaks the rules and an admin clicks on the ban button.
Step 2. The ban dialog comes up, along with a link to the ban log.
Step 3. The admin clicks on the ban log and determines if the user in question has broken the rules before, and if so, are the previous bans recent enough to still count towards a longer ban.
Step 4. The admin applies the ban with the correct time and user title.
There are no "strikes", just a ban log that lists all the bans we've done since the new system was put into place back in June 2007. There isn't a variable somewhere that lists how many strikes you have, so there's no way that anyone could possibly forget to remove one. Part of the reason why we changed the time for strike expiration to two months was to make it easier on us to figure out whether or not someone's strike has expired, because we're doing all the math in our heads.