If you're removing columns, you should use explicit `up` and `down` methods rather than `change`. Usually ActiveRecord can infer what the opposite action is when doing a rollback but in the case of a remove or delete action it doesn't have enough information. The opposite of `remove_column` is `add_column`, but in addition to the table and column name it also needs to know the type and constraints. Your migration might look something like:

```ruby
def up
  remove_column :events, :latitude
  remove_column :events, :longitude
end

def down
  add_column :events, :latitude, :float, null: false
  add_column :events, :longitude, :float, null: false
end
```

We needed to specify `float` and `null: false` so that ActiveRecord can recreate what we dropped if we had to rollback for some reason.