Replying here, since this may be of interest to other users too.
Deleting an inactive game is not a requirement, but it is considered a courtesy. However, if an inactive game is left sitting about for long enough, then the game will be flagged for deletion and, eventually, removed from the site.
For more information, look under "Are games ever deleted from the site" here;
/help/?t=faqs&page=generalfaq