To perform bulk actions on your data, you need to define API workflows that you will call from the Data tab, in the Editor. The process starts by enabling backend workflows in Settings > API, heading to the "Backend workflows" page of your app, and creating an API workflow that takes one parameter and does some action with it. If you are only planning to use this API workflow internally (e.g. for a bulk operation), it does not need to be exposed publicly. The parameter type should be the type of data you want to process. Such an API workflow should not take another parameter, as when the bulk operation is running; it will call this workflow with the thing as the only parameter.