Remove enum value with gem sequel

Question

I have a db - Postgresql v11.3 and Sequel with pg_enum, so how I can remove value from enum type? For example, need change column enum type :

Sequel.migration do
    up do
        removed_values = %w["val1" "val2"]
        remove_enum_value= (:old_enum_type, removed_values) 


        create_enum(
            :enum_column,
            %w[val3 val4]
        )

        alter_table :users do
            set_column_type(
                :enum_column,
                'enum_column[]',
                using: 'old_enum_column::text[]:::enum_column[]'
            )
            set_column_default :enum_column, '{}'
        end
    end
end

New enum type same as previous, with little different - new type doesn't have a some values. But, may be situation if somebody use missing values - migration will be crashed. Unfortunatly, pg_enum don't have a method, that will able simple remove enum value

Answer 1

If you review https://www.postgresql.org/docs/12/sql-altertype.html, you will see that PostgreSQL supports adding and renaming enum values, but not removing them.