Du'a to remove all sins

اللَّهُمَّ إِنَّكَ عَفُوٌّ تُحِبُّ الْعَفْوَ فَاعْفُ عَنَّا

Allāhumma innaka 'afuwwun tuḥibbu al-'afwa fa'fu 'annā

O Allah, indeed You are Pardoning; You love pardon, so pardon us.

Adapted in the plural for group supplication from Jāmiʿ al-Tirmidhī 3513, which reads "fa'fu 'annī" (pardon me).