Ability to remove posts from trips

slices/admin/repos/post_trip_repo.rb

@@ -2,6 +2,10 @@ module Admin
   module Repos
     class PostTripRepo < Adamantium::Repo[:post_trips]
       commands :create
+
+      def remove(trip_id:, post_id:)
+        post_trips.where(trip_id: trip_id, post_id: post_id).delete
+      end
     end
   end
 end