Reduction of data file size for NA61/SHINE beyond 2020

NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) is a multi-purpose experimental facility currently hadron production in hadron-proton, hadron-nucleus and nucleus-nucleus collisions at the CERN Super Proton Synchrotron. In this experiment, the Data Acquisition System generates raw files with size on the order of $10^9$ Bytes, and reconstructed files on the order of $10^8$ Bytes. In both cases, the reduction of the data files is critical for completing the planned physics program. This report describes a post-reconstruction process which removes of the clusters not associated to tracks and possible future work to obtain a further reduction of the reconstructed files.