Tools > Measure > Delete All Collections
Removes all measurement collections and any associated measurements. You do not need to delete the measurements before deleting all of the collections.
You do not need to delete the measurements before deleting the collections.
To see the measurements contained in each collection before deleting them, click Tools > Measure > Edit Collections, select a collection Name, and then click the Display option to view the measurements in the Main view.
You can also access this command by pressing CTRL+D or by clicking Delete All Collections on the Tools toolbar.