You don't. Data is transferred automatically to the NOAO archive so you can download the data from there. All raw DECam data is processed by a Community Pipeline managed by NOAO and delivers reduced images (single and stacked) with astrometric and rough photometric solutions (see more detail in the NOAO Data Handbook [1]). You will be contacted by e-mail by NOAO when your reduced data is ready for downloading. The process may take a few weeks after your observations are finished.
Links
[1] http://www.ctio.noao.edu/noao/sites/default/files/DECam/DECamUG_v2.0.5-ARW.pdf