When the Sentral Canvas integration was first made, the option to set a status to “completed” was not part of the integration. The schools that informed the direction for the integration wanted their Year 12 students to still have access to the courses they were in previously, so asked for Year 12 students to not be removed from prior subjects. Sentral also requires student status in Canvas to be “active” in order to provide the syncing of marks and outcomes from Canvas to Sentral.
You should be able to manually remove students from the course as an Admin in Canvas after clicking on the Rollover Data button and the sync will no longer add those students back into those previous courses. The rollover at the start of the school year generally should take care of this.