If you have a single case design with a small effect size, you should still report your authentic research without manipulation. You should not reduce cases or file the report. There may however be publication bias, because many reviewers only approve large effects. But this can result in overestimation of tx effects found in other studies in which research in manipulated and/or resubmitted. We need to be mindful that negatives outcomes are just as important to our research and treatment as positive outcomes. There are evidenced based practice reviews that can control some of the bias and you should advocate for this, so that your quality research gets published regardless of effect size.