Only the Beta - Original & Budget - Campervan comes with a backseat, which means it can seat up to 4 people.
You can turn the backseat (swivel) as it is part of the bed set-up but you cannot fold it down or remove it. The backseat is fixed and different from a regular car backseat. It swivels.
Here are some examples of what you can do with the swivelling backseat of the Beta. The photos below show the different positions you can turn the backseat into.