There is no way to turn off the routines or make one-time changes. If you have a Monday off, in order to turn off the notifications you have to edit every step in the routine separately and turn off Mondays for that step. Then you have to turn it on again for every step if you want it to resume again the next week.
The general reminder feature goes off even on days with no routine set. Turning off reminders does not stop the notifications for your routines.
This is not ready to be a paid app.
Res Cogitans about Morning Routine: Habit Tracker, v2.1.0