From FreeCAD Documentation
- Select one or more constraints.
- There are several ways to invoke the tool:
- Press the Activate/deactivate constraint button.
- Select the Sketch → Sketcher constraints → Activate/deactivate constraint option from the menu.
- introduced in version 1.0: Right-click in the 3D view and select the Activate/deactivate constraint option from the context menu.
- In the Constraints section of the Sketcher Dialog select the Activate or Deactivate option from the context menu. The offered option depends on the state of the constraint under the cursor.
- Use the keyboard shortcut: K then Z.
- Active selected constraints are deactivated and turn grey (default color), while deactivated selected constraints are activated and return to red (default color).