To save a modified workflow we can either do it from workflow builder or WFLOAD but to a remove a workflow or to delete a workflow definition completely we dont have any standard way to do it.
wfrmitt.sql deletes all data in all Oracle Workflow design time and runtime tables for a particular item type. This script prompts you for an item type from a list of valid item types.
Use the script as follows:
sqlplus < apps /apps pwd > @$FND_TOP/SQL/wfrmitt
Warning: This script deletes ALL workflow data for a specified item type and this cannot be undone