Hi Bing,
Currently, we do have trigger for “when a file is created” and “when a file is modified”, but there is not trigger can be used for “When a file is deleted”.
About available triggers and actions for SharePoint, please check it at here:
https://docs.microsoft.com/en-us/connectors/sharepointonline/
About the on delete trigger for SharePoint file, please submit an idea at Flow Ideas Forum, I will help collect and report it on my side, hope it can be considered in the future releases:
https://powerusers.microsoft.com/t5/Flow-Ideas/idb-p/FlowIdeas
In your scenario, you may consider using the following triggers according to your needs, than adding the “send approval email” action after the trigger.
Please have a try with it. If you need more help, please feel free post back.
Best regards,
Mabel Mao
