Answers for "rails migration remove field command line"

how to remove columns from rails

rails generate migration RemoveFieldNameFromTableName field_name:datatype

remove_column :table_name, :column_name

rails remove column from model

class RemoveCountryFromSampleApps < ActiveRecord::Migration[5.0]
  def change
    remove_column :sample_apps, :country, :string
  end
end