For mass deletion filtered by a specific record attribute, we recommend following a strategy originally shared by Chuck Meyers in our Algolia discourse community.
Instead of performing a search for the records you want to delete, use the browseObjects method and include a filter for the attribute value(s).
You can limit the response to objectIDs for the sake of efficiency, and then pass the array of objectIds to deleteObjects for batch deletion.
We have more details about this with code examples here.