Your drawing is highlighted blue when taking a measurement.
This happens because the document contains at least one Viewport which defines the scale and units of measurement.
You can remove the unwanted viewport by following these steps:
- Open the Measurements (Alt+U) panel and expand the Viewports dropdown.
- In the Viewports list, click to highlight the viewport you want to delete.
- Click the Clear All Viewports icon .
- Select Clear All From Page to delete the highlighted viewport from the current page;
Select Clear All From Document to remove viewports from the entire document.