Changing the Asset Type of an existing Asset

 How do you change the asset type of an existing asset?  When I go into Asset Workbench and try to update the field it says that it is not updatable.  In addition to that, the drop down list only displays (Capital, CIP, and Group).  I want to change the asset type from Capital to Expense.  The asset was originally set up in error and should have been expense.  Thank you.