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