Hi @MRamadan90 ,
Please try and:
1. Set OnChange of the 'Reserve Date' DatePicker with below to create a collection with reserved time based on the selected date:
ClearCollect(colResTime,AddColumns(Filter('Online Flu Sign up', 'Reservation Date' = ReservationDateDataCardValue.SelectedDate).'Reservation Time'),"ResTime",'Reservation Time'.Value).ResTime)
2. Set Items of the Combo box to:
Filter(Choices('Online Flu Sign up'.'Reservation Time'), !(Value in colResTime))
Hope this helps.
Best regards,
Community Support Team _ Jeffer Ni
If this post helps, then please consider Accept it as the solution to help the other members find it.