snippet.rb

form_names = AdHocTemplate.active.map(&:canonical_name)
states = %w(pending in_progress submitted)

Contact.all.each do |c|
  form_names.each do |form|
    forms = AdHocForm.where(:template_canonical_name => form, :contact_id => c.id).all
    next if forms.empty?
    forms = forms.to_a.sort{|a, b| states.index(a.aasm_state) <=> states.index(b.aasm_state)}
    forms.pop
    forms.each{|f| f.destroy}
  end
end