You don’t have to delete anything, a god roll is still a god roll. You can infuse it to power up its light as many times as you want. It doesn’t just suddenly become obsolete, the only thing is new stuff shows up with better stats or that new crafting feature that allows you to craft any god roll you want but those old rolls you have will always work just fine. Destiny is a love service game and things will always be changing, Ive learned this since back in D1. My suggestion is to stop grinding so damn much and just play the game for what it is, I always expect something better each season and each new expansion.