It is not currently possible to hide or remove days of the week from your WhenToHelp displays. The week is always seven days long in our system, and all seven days are always visible.
In the meantime, you might consider marking those days ‘Closed’. Our system does not offer a simple means of labeling days, but you can create a Position called ‘Closed’ and then create one shift for that position on your day off. This can act as a reminder that no one should be scheduled that day. Since you will NOT allow any helpers to work this position, no one will be assigned to the shift if you use AutoFill →More