I think if the person who made this Kimuchi knew how I washed it off before I eat it, it would make them sad.
この場合、次のような言い方ができますよ。
ーI think if the person who made this Kimuchi knew how I washed it off before I eat it, it would make them sad.
「このキムチ作った人が、私がキムチを洗っているのを知ったら悲しむだろうな」
to wash off で「洗い流す」
ご参考まで!