Change ownership of scheduled messages

We have three messages scheduled weekly via messaging workflows.  At the time, they were created using the employee's xMatters account.  Now, we have an "admin" account and would like to change the ownership of the messaging from the individual to the "admin" account.

I'm looking for an alternative and practical solution rather than recreating the messages with the "admin" account and deleting the current messages.  I do not see a means to reassign the messages.

Does anyone know how we may change the ownership given the above?  

Thanks,

John