Well i tried everything said above but nothing worked.

Please help me solve this.

Hi,

If you need to disable the emails sending to customers or any one,
You can remove the outgoing mail server setted in the settings -> Discuss -> Outgoing mail server

OR

If you need to deactivate any specific mail that send from the schedule action, you can deactivate itexample
settings ->technical ->Automation->scheduled action
select the scheduled action that you need to deactivate, and disable the active boolean

Hope it helps