Pls help me write codings to remove CP

I got code to add cp

message = randint(1,M,4); %Assuming QPSK symbols

length_cyclic = 15;

starting =M - length_cyclic + 1;

cyclic_prefix = message(starting : end);

prefixed = horzcat(cyclic_prefix,message);

[Janet]

I want to remove in receiver side