As mentioned here, we don’t recommend to mutate existing fields in the enriched event. Recommended way is returning a new context instead.
i know the recommended why but we have some need to change it . is their any way by we can do it
It’s not recommended but afaik there’s nothing to stop you mutating fields already in the event. The main reason it is discouraged is that events aren’t validated after being returned so if you make a change that doesn’t conform to what the loader / data warehouse expects this will fail to sink to the data warehouse.