The length of the chain can be easily adapted by using a chain tool (https://www.decathlon.fr/derive-chaine-velo-900-id_8351521.html) and fitting the quick release that comes in the pack.
Dismantling
Easy to dismantle using a quick-release chain tool (https://www.decathlon.fr/pince-attache-rapide-chaine-id_8352339.html) and/or standard chain tool (https://www.decathlon.fr/derive-chaine-velo-900-id_8351521.ht)