Hi, I want to second Abdullah's comment. Removing a check error message from the message container is usually not a good approach. MDGM example: If Activation fails in reuse area and you modify the messages passed from the backend, MDG might think the activation was successful even though it wasn't.
To deactivate backend checks (or other checks), you can use MDG-IMG activity "Configure Properties of Change Request Step".
To modify mandatory field settings from the backend, MDGM provide transaction OMSR. Other applications have different settings.
So basically, it depends on your use case.
Regards, Ingo Bruß