The antonyms for the phrase "creating anew" would be destroying, annihilating, eradicating, obliterating, wiping out, demolishing. They all mean to put an end to something that once existed or to prevent it from existing in the future. When someone or something destroys, they break down or completely ruin the structure or function of something. The word annihilating means to destroy completely, to utterly wipe out, to reduce something to nothing. Eradicating connotes uprooting, eliminating something completery, removing it completely from existence. Obliterating means to erase, make invisible or reduce to ashes.
In conclusion, the antonyms of creating anew represent the opposite of generating fresh matter, and instead denotes destruction and the end of already established matter.