Use the script as follows:
sqlplus <user/pwd> @wfrmall
Warning: This script deletes ALL workflow definitions. Do not use this script unless you are absolutely sure you want to remove all workflow data from your runtime and design time tables.
Once you run this script, you should also reload the workflow definitions for the Standard, System:Mailer, and System:Error item types stored in the files wfstd.wft, wfmail.wft, and wferror.wft, respectively.