Solved by ecdrid in post #8 
              
              
                search for named_parameters… 
here’s how it’s done, 
print('Training these layers')
for name,param in model.named_parameters():
    if param.requires_grad is True:
        print(name, param.requires_grad)

I hope you can flip the requires_grad as per the need… 
Secondly don’t pass model.parameters() …