It is likely you have the runtime:

sudo yum install -y libnccl

But not the development environment:

sudo yum install -y libnccl-devel

As an alternative, since you have the HPC tag, most HPC cluster tend to have their code under modules (env mod, or lmod) and those are usually outside /usr. You can look with

module avail nccl

If it is there you could load the module and should have access to the development environment.

For the actual finding, If it is in a module, the the previous command will tell, and you can check in the module file to see if any variable like nccl_home is set which might make it easier. You can also use l config which might work

ldconfig -p | grep libnccl

Finally, specific to this case, try to run nvidia-smi if it is installed (and in path), it should print an output indicating the version (and maybe location?) of nccl.