Possible to CREATE EVENT NOTIFICATION with a different owner?
I thought that ALTER AUTHORIZATION might offer a way to transfer ownership, but no, according to the docs (emphasis mine):


  Ownership of the following entities cannot be transferred: &lt;many things&gt; and event notifications.


So, script them, drop them, and re-create them under a more generic account that is not tied to an employee.

This is similar to things like the ANSI_NULLS setting for tables (which I dealt with recently re: persisted computed columns).