removing flat battery

old scot

hi , hoping someone can help, have 2006 Elddis autoquest 180 on boxer chasis withwith 2.2 Peugeot engine. battery was flat and when I tried to remove it, I fond that the rear positive terminal appears to be covered with some type of terminal wiring block
with no apparent means to access terminal....can anyone advise please ...likely going to be yet another senior moment