Remove redundant validation and method

app/models/sales_log.rb

@@ -561,8 +561,4 @@ class SalesLog < Log
   def is_firststair?
     firststair == 1
   end
-
-  def is_not_firststair?
-    firststair != 1
-  end
 end

app/models/validations/sales/sale_information_validations.rb

@@ -363,11 +363,6 @@ module Validations::Sales::SaleInformationValidations
       record.errors.add :numstair, I18n.t("validations.sales.sale_information.numstair.must_be_greater_than_one")
       record.errors.add :firststair, I18n.t("validations.sales.sale_information.firststair.cannot_be_no")
     end
-
-    if record.firststair == 1 && record.numstair > 1
-      record.errors.add :numstair, I18n.t("validations.sales.sale_information.numstair.must_be_one")
-      record.errors.add :firststair, I18n.t("validations.sales.sale_information.firststair.cannot_be_yes")
-    end
   end
 
   def over_tolerance?(expected, actual, tolerance, strict: false)

config/locales/validations/sales/sale_information.en.yml

@@ -127,7 +127,5 @@ en:
           value_over_discounted_max: "The percentage discount multiplied by the purchase price is %{discount_value}. This figure should not be more than £102,400 for properties outside of London."
         numstair:
           must_be_greater_than_one: "The number of staircasing transactions must be greater than 1 when this is not the first staircasing transaction."
-          must_be_one: "The number of staircasing transactions must be 1 when this is the first staircasing transaction."
         firststair:
           cannot_be_no: "The answer to 'Is this the first staircasing transaction?' cannot be 'no' if the number of staircasing transactions is 1."
-          cannot_be_yes: "The answer to 'Is this the first staircasing transaction?' cannot be 'yes' if the number of staircasing transactions is greater than 1."

spec/models/validations/sales/sale_information_validations_spec.rb

@@ -1444,16 +1444,6 @@ RSpec.describe Validations::Sales::SaleInformationValidations do
           expect(record.errors).to be_empty
         end
       end
-
-      context "and numstair is greater than 1" do
-        let(:numstair) { 2 }
-        let(:firststair) { 1 }
-
-        it "adds an error" do
-          expect(record.errors[:numstair]).to include(I18n.t("validations.sales.sale_information.numstair.must_be_one"))
-          expect(record.errors[:firststair]).to include(I18n.t("validations.sales.sale_information.firststair.cannot_be_yes"))
-        end
-      end
     end
   end
 end