Scroll Down and select Action Wizard (Under Customize)
Select New Action
Under files to be processed, select the folder or files that you wish to be processed.
Click the dropdown menu on the left titled Save & Export
Click Save
Click Specify Settings
Click export Files to Alternate Format
Select Plain Text from the drop down menu
Click Save and name your action
To run the action, select it from the Actions List on the Right Hand side of the screen
Note: This crashes fairly frequently and needs some human supervision.