Opening Process Modeler gives error Process is read-only because version <2> is being edited by <us

I am attempting to setup RSS Escalation. 

When K43E08/1 is selected for edit and the Process Modeler is is opened in OMW, a dialog box displays with message:

     This process is read-only because version <2> is being edited by user <user?
     Multiple versions of the same process cannot be edited concurrently.

The Process Instances table contains no records for K43E08, these were all purged.

What can I do to reset the editing flag for this process

thanks

Mick