It depends on how much you want to reduce these harmonic. For sure, you will need to use some kind of filter. What is target application? Give us some more information about which harmonics etc. Also, I would suggest to take a look at Kalman filter.

You can use active filters for to introduce currents against the harmonic currents, with the purpose of eliminate the components.

And another one blatant solution is when you just take the Fourier series and drop everything "redundant" according to your criteria, say, for magnitude or frequency. But filtering, as others suggested, is a conventional method. Search for selective harmonic compensation, for example.

Dear Vivekanandan Kandiannan,

Among the techniques used to harmonic current reduction in power system:  the frequency response modification and the installation of filters (passive, active or hybrids).

I indicate a book for you to implement the codes in MATLAB: “Power System Harmonics: Computer Modelling and Analysis”. Enrique Acha and Manuel Madrigal. John Wiley & Sons, Inc.

Best Regards.

MATLAB help is a useful aid to work with its SIMULINK ..