add the migration

db/migrate/20211118090831_change_armed_forces.rb

@@ -0,0 +1,17 @@
+class ChangeArmedForces < ActiveRecord::Migration[6.1]
+  def up
+    change_table :case_logs, bulk: true do |t|
+      t.remove :armed_forces
+      t.remove :armed_forces_partner
+      t.column :armedforces, :integer
+    end
+  end
+
+  def down
+    change_table :case_logs, bulk: true do |t|
+      t.remove :armedforces
+      t.column :armed_forces, :string
+      t.column :armed_forces_partner, :string
+    end
+  end
+end