Welcome Moemen Ahamed:
There are some cases where the minor drains like the sink and shower empty into a floor drain, which is then called the 'master drain'. In those cases the minor drains do not have a trap in them and, if hooked up direct without the trap in the floor drain, would allow foul odors to come into the house.
In my state, if there are more than 3 fixtures, a floor drain is required.
I would leave the floor drain if it were mine.