To Control Dimension Line Visibility (AutoCAD Mechanical Toolset)

In the drawing area, double-click the dimension you want to edit. The Power Dimensioning Ribbon Contextual Tab displays.
Click Power Dimensioning tabFormat panelEdit Geometry. Find
In the graphic showing the dimension, click the first dimension line and second dimension line so that both arrowheads are shaded.
Note:
To locate the fist dimension line and second dimension line, move the pointer over the graphic and observe the tooltip.
Click OK.
Click Power Dimensioning tabClose panel Close Editor. Find