Possible sync delete options include "ignore deletes", "sync deletes" and "sync deletes and delete extra files on Folder B".
The ignore deletes option causes the task to ignore any files or folders deleted from Folder A in a one-way sync task or ignore any files or folders deleted from either Folder A or Folder B in a two-way sync task. New files, updated files and renamed files and folders are still replicated.
The sync deletes option causes the task to delete from Folder B any files or folders deleted from Folder A in a one-way sync task or delete from the other folder any files or folders deleted from either Folder A or Folder B in a two-way sync task. New files, updated files and renamed files and folders are also replicated. This option is the default for new two-way sync tasks.
The sync deletes and delete extra files on Folder B option is only available to one-way tasks. This option behaves like "sync deletes" with one exception: any "extra" files or folders created or renamed on Folder B by anything other than this sync task will automatically be deleted. This option is the default for new one-way sync tasks.