Deleted schedules do not stay deleted.

When a schedule is deleted you may find that a default schedule is then generated and applied to the room. The behaviour to be expected. By design each room must have a schedule assigned to it.
 
However, this does not mean that the schedule must be followed.
 
You can set a room to manual mode by heading to the Home/Control page of the Wiser Home app > Tap on a room name > another screen will appear showing the boost icon and slide bar > Tap the 3 dots in the top right hand corner > From here you can edit or assign a schedule along with deactivating the schedules by turning off the "Follow schedule" toggle ("Follow schedule" will only appear when a schedule is assigned to the room in question).
 
Once in manual mode the room will remain as set until another change is made.

For further information please see the Climate control page of our Wiser Home – System User Guide (UK, Ireland)