I don't have now a D365BC sandbox to check if report 357 (Copy Company) has events exposed to subscribe.
If yes, you can subscribe to the event fired after the copy and then start your custom code for deleting data.
Otherwise, you can create your custom Copy Company function and disable the standard one. The standard Copy Company report is just a simple report that asks for a new company name and does the following:
COPYCOMPANY(Name,NewCompanyName);
After that code, you can start your record deletion.