With the World of Warcraft 10.0 UI rework, the option to move raid frames around is unfortunately missing outside of edit mode. This simple AddOn adds a drag handle to the default raid frames and raid-style party frames, allowing them to be dragged freely without overwriting positions set in edit mode. Frames will revert to their saved layout position when the UI reloads.
https://www.curseforge.com/wow/addons/movable-raid-party-frames