No one has the authority to remove a label that the shipper had affixed unless there is concrete grounds that the label is incorrect.
Moreover, if the substance fits the EU description of Mar ne pollutant, it will be a breach of the EU regulations if the shipment is dispatched without the Environmentally Hazardous Mar ing. The forwarder must be held responsible for removing a label without justification. DGR 220.127.116.11 and 18.104.22.168 Note clearly state that Environmentally Hazardous substances (aquatic environment) are those that meet the criteria in 2.9.3 of the UN Model Regulations or that meet criteria in national or international regulations established by the appropriate authority of the State of origin, transit or destination.
They must be identified with the Environmentally Hazardous Mar ing. EU is particularly strict on this rule and non-compliance will constitute a breach of the EU regulations. You need to explain this to your forwarder.