As long as he did not cancel the Soul Contract from his side, there should have been no way for Vicious to liberate himself from it.
This was similar to how the Deathless Monarch, despite being a God Monarch, was unable to free himself from a Soul Contract on his own.
In order to prevent Vicious from turning against him, he had made sure to seal a Soul Contract with him while they were on the Master Teacher Continent. This way, even if Vicious gained the ability to escape from the Book of Heaven's Path, he would still be bound by the laws of the Soul Contract.
"Ah, the Soul Contract? It was a headache to me for quite a while, but I realized that my worry was unfounded. What I have in me is the malignant energy that can even neutralize the heavens! As long as I can obtain sufficient strength, it isn't too difficult to tear apart that farce of a Soul Contract!" Vicious smirked.
