When the legend generates you may find that you want to move this to other areas on the plan. This could be due to wanting to move it closer to certain items or it may be covering a part of the plan you want to take off/view.
To move the legend, ensure you have the Select tool enabled. The select tool is found under Home under the Edit group.
Fig 1. Select tool under the Home tab in the Edit group
Once the select tool is selected, click on your legend in the viewport, an orange crosshair cursor will appear on the upper left corner of the legend itself.
Clicking and then dragging on this cursor will allow you to move the legend anywhere on the viewport.
Fig 2. Legend with cursor