How to cancel stack protection

I have tried to add `-fno-stack-protector` to /cb-multios/CMakeLists.txt: +56 

In addition, I also checked /cb-multios/build/challenges/Accel/CMakeFiles/Accel.dir/flags.make, 
Ｃ_FLAGS = -fno-builtin -w -g -m32 -fno-stack-protector -O0 -std=gnu99 

But stack canary is still not closed