How to filter off the noise in raw EEG signal

I want to denoise in raw EEG data with MATLAB, but there is something wrong with the program. I couldn't run the code. Could you possibly help me to solve this problem, please? The program is below.

    %%Denoise program
    % This section is only pre-processing the original data 
    % after denosing and re-arranging the labels
    % s is the raw biosignal data, having 4 channels
    % SampleRate is sampling rate of EEG signals ( the data points per second)
    % InputEEG and OutputEEG are single channel EEG signal. 

    clear all

    % Notch filter
    w0 = 50*(2/SampleRate);
    [b,a] = iirnotch(w0, w0/35); %iirnotch is notch filter (a built in function in Matlab)
    s = filtfilt(b, a, s);

    % Bandpass filter
    s(:,1) = bpfilter(s(:,1), [0.3 SampleRate/2]); %bpfilter is another built filter. 
    s(:,2:3) = bpfilter(s(:,2:3), [0.3 SampleRate/2]);
    s(:,4) = bpfilter(s(:,4), [10 SampleRate/2]);

    % Downsample by 2
    s = s(1:2:end,:);
    HDR.SampleRate = HDR.SampleRate/2;

    % Replace NaN and Inf with 0
    s(isnan(s)) = 0;
    s(isinf(s)) = 0;

    % Convert to single
    s = single(s);