 As they're a facilitator, you are responsible for making sure things stay on time, making sure the goals and objectives of the workshop are achieved, and making sure that too much discussion doesn't go off topic. It can be really challenging to keep control over the whole group without sounding rude or unprofessional when you need to cut things off and keep the workshop moving. So what I like to do that makes this 10 times easier when I'm running a workshop is to explain the facilitator role and responsibilities at the very beginning of the workshop. It can just take you two or three minutes and maybe have something on your screen as well that explains these responsibilities and pre-warns people that you might cut them off during a discussion when the information isn't helping us move forward with the challenge.