CITROEN Grand C4 PICASSO Owner's Handbook Manual page 96

Comfort
Flat floor
Each seat can be folded onto the floor to vary
the the space available in the boot.
Folding a seat
Place the seats in the fully back position.
94
From the outside
Pull firmly upwards on strap C, as indicated
by the arrow, to unlock the seat; keep
pulling until the seat is fully folded.
Push the seat backrest gently forwards
so that the backrest folds onto the seat
cushion. The assembly lowers onto the
floor.
From the boot, when loading for example
You can fold the second-row seats from the
boot, after first folding the third-row seats.
Pull on the strap D to release the seat in
question then push forwards lightly on the
backrest.
To avoid any damage to the mechanism,
the strap D unclips if too much force is
applied. Simply clip it in place again for the
system to be operational again.