out with the old and in with the new (idiom)

to wash out; (fig.) to cull; to weed out; to eliminate; to die out; to phase out

(literary) to eliminate; to delete

elimination of the weak (cf. 優勝劣汰|优胜劣汰[you1 sheng4 lie4 tai4])

(dialect) dirty; to mock sb

to wash away; to eradicate