Proper disposal of resin is key for a greener tomorrow.
Any leftover resin should be allowed to fully cure and harden in the scuttle or bucket it was mixed in, at which point it becomes an inert plastic. This can then be disposed of as another other hard plastic, typically this would be general waste.
Alternatively, cured resin paints can sometimes be taken to a recycling plant where it would be granulated to be reused/repurposed.
Regarding containers, our cardboard boxes can naturally be recycled widely. If you want to get rid of a used epoxy container however, ideally ensure as much has been used in the project and the container is as empty as possible, before disposing safely in general waste once it has cured.
If you are missing either Part A or B, and have no means to safely cure the resin before disposal, DO NOT throw it away in its liquid form. In this state, it is toxic to the environment and can damage what it comes into contact with. You should call in disposal specialists in this case.