ironass, May 27, 2019 : There is no, "simple way". There is only the right way and the wrong way. The latter could, "brick", your phone. I take it that you have read and researched the ramifications of rooting your phone. That you will only be able to download and install the full OnePlus firmware updates, 1.6GB+, once rooted, (no more incremental updates), and that you will need to re-enable rooting after each update and that certain apps may not class your device as secure afterwards, without you taking further steps. Have you already unlocked your bootloader? If not, you will need to do that before rooting and everything on your phone will be wiped during the process. Still want to go ahead?