Being good now doesn’t fix it. No need trying to hide your sins from God. He knows what you did and only He can take away your guilt, and He will when you confess it to Him.
“Wash me clean from my guilt.
Purify me from my sin.”
“Come now, let’s settle this,”
says the Lord.
“Though your sins are like scarlet,
I will make them as white as snow.
Though they are red like crimson,
I will make them as white as wool.”