To active the tool press SHIFT + CTRL + A and choose Annotate tool.

Delete All = Delete all Sketch strokes.

Delete visible = Delete only visible strokes.

Show/Hide Strokes = Toggle with Hide/Unhide

Angle fallout = smaller number here and quicker stroke will hide from screen.

Show strokes front/back = If you want to see stroke from back and front

Distance fallout = smaller number here and quicker strokes will hide when zooming out.

Overall opacity = Control for all strokes opacity

Apply symmetry = This will apply symmetry when you sketch ether front or top view. Side view is not using symmetry this even if this is turned on.

Strokes per object = You can isolate strokes per selected object.