You may need to 'blank a control' in order to reset it or clear out the data for some reason. This KB explains how to use a simple Transfer Data rule to blank out a control.
Before You Begin
Make sure you have a View and Form with the controls you would like to blank out.
1. Open your View/Form.
2. Create or open the rule of which you would like the value to be emptied out of.
3. Add a new Transfer Data rule and check the box next to the control you would like to empty. See the following screenshot.
4. Test your View/Form to see that the value is blanked out.