If you want to delete many objects (say many Participants, Specimens, etc.), you can do it via CSV import.
Be very careful since-deleted objects cannot be reverted back.
Tips for performing massive bulk imports
Perform such import during off-peak hours. You can enable the 'System Lockdown' feature to stop other users from logging into the system.
Delete objects which have many dependent objects can take a long time.
The database locks the tables from which the data is being deleted. Set the pre-validate to a small number 100 or 200 to ensure the locks are not held for a long time.