Dale worked for the meat supplier, Harries & Harries. After the supplier's "Cash Cow" was mercy killed by Owen Harper, Torchwood Three gave him retcon to forget everything that happened. (TW: Meat)
According to Jack, he was so disgusted by what Harries & Harries had done that he had retconned the staff and employees (presumably including Dale) back to his teens. (The Torchwood Archives)