which view your organization is using BPV? and if you guys perform Change always with Task and not through Change Implementer as per the ITIL practise... then may be try setting Change Implementer Assignment Event to Disabled in the Assignment Form under the Application Admin Console--->Standard Configuration--->Assignment for your Company.
or we need to find out the Filter(CHG:CRQ:AssignmentImp_018_AsgRouting) which assigns the Implementer Group and disable that..
most recommended would be:
To find out the workflow which making the Change Implementer to disappear and set the Implementer Fields to Null
Ideally is should be set to NULL and then get disappeared when the Task is being attached to the Change Request...but doing it from the client side may not be helpful...
Having a Filter on the Modify and which checks for (z1D Task Exist!=$NULL$) then set the Change Implementer Fields to NULL.
ya I have noticed that 'General' is the Assignment Event which is being used for the 'Change Implementer' Assignments in the Assignment Form. now this has become tricky to handle it through configuration itself as 'General' would be used for other Assignments as well..
Try to find out the Message Tag which is being used for the Change Implementer Notification in the SYS:Notification Messages Form and if it is of specific then you may go ahead and disable it(but you need to understand that system would never sends the notification for the Change Implementer irrespective of Task is available or not).
You can also search for the Event 'Change Implementer' in the NTE:Notification Event Form and go ahead and disable it as per your need.
If nothing works then you gotta go to code change(may be addition of a new Filter)
(z1D Task Exist!=$NULL$) AND ('Change Implementer Group!=$NULL$)
Set Change Implementer Fields to Null
Here you gotta make sure that the field z1D Task Exist is getting populated rightly as per the logic which determines Task exits or not(there should be codes to do that pls find out and fit it for your scenario)