Use median or averaging filters. For example this is from MATLAB's examples:
https://www.mathworks.com/help/signal/ref/medfilt1.html
% Create the signal
fs = 100;
t = 0:1/fs:1;
x = sin(2*pi*t*3)+0.25*sin(2*pi*t*40);
% Filter
y = medfilt1(x,10);
%Plot the result
plot(t,x,t,y);
legend('Original','Filtered');
legend('boxoff');