You can delete an entire mass court block, or delete individual records in the mass court block.
Open the Mass Court Blocker (Court Scheduler >> Mass Court Blocker) and Choose 'Previous Block Reservations'.
See option # 1 to delete the entire Mass Court Block
See Option # 2 to drill down into the details of the Mass Court Block:
To delete multiple reservations, check the box in the right hand column, and then click 'Delete". This will only delete the selected records, leaving the remaining reservations in place: