Guide Point entities
Guide point entities are finite dashed lines with end points as guides to draw precisely. Guide points do not interfere with regular geometry. Guide points can also be hidden and erased independent of regular geometry. Draw guide points with the Tape Measure tool.
You can use the Move, Rotate, and Erase tools to reorient a guide point.
Hiding/erasing all guide points
Guide points are usually created as a temporary means to build a portion of your model. Keeping too many guide points in your model can decrease SketchUp's inference accuracy and display performance, so you might want to hide guide points as you work or delete all guide points at once when you have finished your model.
Use Edit > Hide to hide the currently selected guide line. Use Edit > Erase Guides to erase all guides in the current context.