as explained in the chapter Vertical List, the list itself does not manage any data. It does not store the data, so there is no functionality to add/remove, etc. the items. The list limit to display the item data from a separate data storage. When you scroll the list, for example, the list loads the exposed items from the storage by using the associated OnLoad slot method. With the implementation of the OnLoad method you provide the interface between the list and your particular data storage.
If you want an item to be removed or added, or you want to change the order of the items, you do this always in the data storage where your items are stored. This storage is an application specific aspect. If your application uses a data base, then your modification affects this data base. If your items are stored in an array, then you modify the content of this array. If your items are managed in a middleware, then you have to ask the middleware to modify the data.
Once you have modified the data storage, you notify the list about this alternation. If you have removed/added items from/to the list, also update the number of items the list actually presents. Thereupon the list will (if necessary) refresh its aspect automatically.
See also: Access list items and views.