Hi @quangtran ,
You can logically (not physically) remove these data running a search where the results are the wrong events and adding at the end the "delete" command.
Remember that by default none user can delete events, so you have to enable the "can_delete" role for your user and I hint to remove this role from your account after events deleting.
As I said, you don't recover disk space because it's a logical deletion.
Ciao.
Giuseppe
