The s6-instance-delete program

s6-instance-delete deletes an existing instance of a currently supervised instanced service.

Interface

     s6-instance-delete [ -X ] [ -t timeout ] servicedir name

s6-instance-delete expects a running, supervised instanced service in servicedir, as well as an existing instance of this service named name (it doesn't matter if the instance is up or down).
It deletes the name instance.
It exits 0.

-X : don't wait. s6-instance-delete will exit right away, without waiting for the instance (and its supervisor) to properly disappear.
-t timeout : if the instance supervisor has not exited after timeout milliseconds, s6-instance-delete will still exit. By default, timeout is 0, which means no time limit.

s6-instance-delete is similar to s6-svunlink, because it uses the same underlying library functions. Under the hood, an instance is a regular service running on a supervision tree that is specific to the instanced service, and s6-instance-delete removes a service directory from that tree.
If the template for the service is logged, then s6-instance-delete will delete both the instance and its logger.
s6-instance-delete and s6-instance-create are relatively expensive operations, because they have to recursively copy or delete directories and use the synchronization mechanism with the instance supervisor, compared to s6-instance-control which only has to send commands to already existing supervisors. If you are going to turn instances on and off on a regular basis, it is more efficient to keep the instance existing and control it with s6-instance-control than it is to repeatedly create and delete it.