A good set of closing remarks will accomplish several principles. The first of these would be a brief summary of what has already been discussed. Making sure you address relevant and concise essential points from your workshop is critical. Essentially, in your closing remarks, ask yourself, "What must leave with knowing?" This will help bring a closing meaning to your remarks. I think that it is always important to thank your audience for their (hopeful) participation and avail yourself to them for any further questions or clarification. This will create the opening for expanded dialogue. Finally, I think the best workshops end with some type of motivation or reflective sentiment. The purpose of your training has been for them to acquire relevant or essential skills. I think a good closing would be for you to discuss with them as to why they are empowered as a result of these skills. There is a certain motivational aspect present here and it's a challenging element to accomplish. Yet, if you can inject some level of this intensity to close out your workshop, your participants leave energized and supercharged in carrying out the skills on which you have instructed them. If this does not work, perhaps spending some time reemphasizing to them how valuable their work, their efforts, and their work with these skills are to the organization as an entity would be an effective closing note to strike.