en_tn/deu/29/20.md

the anger of Yahweh and his jealousy will smolder

Moses compares Yahweh's intense anger to a smoldering fire. This emphasizes God's power to destroy his enemies. AT: "Yahweh's jealous anger will grow like a fire" (See: rc://en/ta/man/translate/figs-metaphor)

that are written

"that I have written" (See: rc://en/ta/man/translate/figs-activepassive)

Yahweh will blot out his name from under heaven

This means God will completely destroy the person and his familay. In the future people will not remember him. See how you translated a similar phrase in Deuteronomy 7:23.