To edit or delete a measurement(s), it needs to be highlighted first with the Edit arrow. This can be done either of two ways-by single clicking on the geometry or by clicking Edit and choosing Single, and then click on the measurement to highlight it. You can grab any of the white boxes to make adjustments. To delete, click the Trashcan icon (or press delete on the keyboard). When you finish making your changes, select Finish Measuring.
TIP #1: You can select multiple measurements, by using Multi-select and drawing a rectangle around the measurements.
TIP #2: You can multi-select specific geometries by holding down the Shift key and clicking on the geometries.