So what? Should we sin because we aren't under Law but under grace? Absolutely not!
References for Romans 6:15
Don't you know that if you offer yourselves to someone as obedient slaves, that you are slaves of the one whom you obey? That's true whether you serve as slaves of sin, which leads to death, or as slaves of the kind of obedience that leads to righteousness.
But thank God that although you used to be slaves of sin, you gave wholehearted obedience to the teaching that was handed down to you, which provides a pattern.
Now that you have been set free from sin, you have become slaves of righteousness.
(I'm speaking with ordinary metaphors because of your limitations.) Once, you offered the parts of your body to be used as slaves to impurity and to lawless behavior that leads to still more lawless behavior. Now, you should present the parts of your body as slaves to righteousness, which makes your lives holy.
When you were slaves of sin, you were free from the control of righteousness.
What consequences did you get from doing things that you are now ashamed of? The outcome of those things is death.
But now that you have been set free from sin and become slaves to God, you have the consequence of a holy life, and the outcome is eternal life.
The wages that sin pays are death, but God's gift is eternal life in Christ Jesus our Lord.