I have a 2022 Kamiq SEL and have just discovered after a struggle trying to load a long flat pack item in IKEA that it cannot be removed! Absolutely ridiculous. Ended up phoning the dealership out of desperation and they said the same. The button on the side is only for moving it up and down however you can remove the rear seat headrests. After a struggle I was able to wedge the 1.8m flat pack diagonally from the boot and my passenger squashed in one rear seat.

 

I confirm video above; it's not obvious but finally this did the trick for me so I could fit seat covers

I saw that video about a hidden button but it does not work for my 2022 model