He told you to do it, using His Name. After calling each demon or group of demons out, take a deep breath and blow out though your mouth. You don't have to feel or see anything to be set free. No one knows all the answers, but I know when you blow out it helps dislodge demons. Fill all the nooks and crannies where all the demons have left.
Spiritual warfare is necessary all during the day.
Even a satanist can be set free. I read that most homosexuals wished that they could stop being homosexual. You MUST be Saved before you can cast demons OUT of yourself and others. I repent Lord. Come into my life.