diff --git a/web/overlay_manager.js b/web/overlay_manager.js
index 233c9f594..891e3a253 100644
--- a/web/overlay_manager.js
+++ b/web/overlay_manager.js
@@ -42,20 +42,6 @@ class OverlayManager {
     });
   }
 
-  /**
-   * @param {HTMLDialogElement} dialog - The overlay's DOM element.
-   * @returns {Promise} A promise that is resolved when the overlay has been
-   *                    unregistered.
-   */
-  async unregister(dialog) {
-    if (!this.#overlays.has(dialog)) {
-      throw new Error("The overlay does not exist.");
-    } else if (this.#active === dialog) {
-      throw new Error("The overlay cannot be removed while it is active.");
-    }
-    this.#overlays.delete(dialog);
-  }
-
   /**
    * @param {HTMLDialogElement} dialog - The overlay's DOM element.
    * @returns {Promise} A promise that is resolved when the overlay has been