Chapter 9 of Mary Shelley's Frankenstein presents a very traumatized and troubled Victor. He admits that he had always lived his life having what he calls "good intentions". He also acknowledges that his passion has always been to be of help and “good use” to others.
However, now he says that he has gone from satisfaction to remorse, guilt, and self-torture. Of course, this torture and guilt comes out of the havoc that Victor’s creature has caused in the family of his creator once the monster realized that he was a mere caprice from a semi-mad and arrogant scientist that wanted to play God. Moreover, the creature was mistreated terribly, wandered the world alone and in hiding, and was deemed a “monster”. It is no wonder that he wanted to destroy his maker.
That being said, Victor might be taking himself out of context when he says that he always had “good intentions” and wanted to be of “good use” to the world. Maybe he did once, but he ended up essentially just living up to this one obsession of creating or causing “life”.
Back to your question, now that Victor realizes that his life has changed drastically from happiness to pain, he wants to level up by destroying the monster, thus avenging the deaths of William and Justine. He now switches from pain and guilt to pure anger and fury toward the creature. These emotions fuel up his plan to finish the monster. His obsession is now to get rid of it.
When I thought of him, I gnashed my teeth, my eyes became inflamed, and I ardently wished to extinguish that life which I had so thoughtlessly bestowed. When I reflected on his crimes and malice, my hatred and revenge burst all bounds of moderation. I would have made a pilgrimage to the highest peak of the Andes, could I, when there, have precipitated him to their base. I wished to see him again, that I might wreak the utmost extent of abhorrence on his head...
Basically what we have is a man gone from happy, to tortured, to angry, in one same lifetime, all because of the actions that he committed; because he did not take into account that bringing a life into the world meant keeping up with it as well. His obsession and ambition were such that they blinded him to that reality. Unfortunately for Victor, he will have to learn to live with that regret, since he will never be truly able to destroy his creation by his own hands.