remove currency model and all references

app/models/sell_crypto_order.rb

@@ -10,17 +10,14 @@
 #  status                :string           not null
 #  created_at            :datetime         not null
 #  updated_at            :datetime         not null
-#  currency_id           :bigint           not null
 #  user_id               :bigint           not null
 #
 # Indexes
 #
-#  index_sell_crypto_orders_on_currency_id  (currency_id)
-#  index_sell_crypto_orders_on_user_id      (user_id)
+#  index_sell_crypto_orders_on_user_id  (user_id)
 #
 # Foreign Keys
 #
-#  fk_rails_...  (currency_id => currencies.id)
 #  fk_rails_...  (user_id => users.id)
 #
 class SellCryptoOrder < ApplicationRecord
@@ -28,7 +25,6 @@ class SellCryptoOrder < ApplicationRecord
   include Notifiable
 
   belongs_to :user
-  belongs_to :currency
 
   monetize :received_amount_cents
 
@@ -41,7 +37,7 @@ class SellCryptoOrder < ApplicationRecord
     "
     💸 New sell crypto order! 💸\n
     user: #{user.email} \n
-    amount: #{paid_amount} #{currency.name}
+    amount: #{paid_amount} CAKE
     "
   end
 end