Hi Olivier,
The administration of fault definitions can be achieved using the Diagnostics Adapter. Please see this guide for more information. The Diagnostics adapter can be used to create, edit, and mark fault definitions as obsolete.
The table fail_mode has a column obsolete_bool. When set to 0, it will set a fault definition as obsolete. The fault definition will still appear in the fault definition search, but it will no longer appear as a selectable fault definition when raising a fault.
It would be best to set this Boolean to 1, and also to change the name of the fault definition to ensure that all stakeholders to this process have visual cues that a fault definition is obsolete.