To do this requires the use of a premium action, so you will need to have the appropriate licensing to use premium connectors. This is from a rather large workflow, so I will just show the pertinent section:
After your approval, add a switch that contains the values of the approval options. You will use the default switch to handle when the requester cancels the approval. With the key part for checking if the approval was cancelled here:
You will get the Approval from table with the Dataverse Get a row by ID action with the Approval ID. Then add a condition to check if the Status Reason is equal to 192350006. If it is, it was canceled, and you can do what you want on the yes side of the condition. I send myself an e-mail if it wasn't canceled since that would mean some other outcome that wasn't expected occurred. So far, that has never happened. 🙂
