Is it possible to un-manifest?

You can un-manifest by either forgetting or by counter-manifesting.

Forgetting is the closest you can come to unknowing something. By forgetting past problems while holding onto the knowledge learned from lessons, you can avoid repeating cycles.  

For example, when Farah thinks back to her childhood, she remembers being lonely. As a 30 year old she decides to connect with her True Self and discovers that many of her current issues relate back to those adolescent years. She decides to focus on the times when she was not lonely. She remembers hanging out with her best friend, laughing with the girls in her dance class, and going shopping with her cousins. Eventually, Farah forgets the lonely times and only thinks of times when she felt accepted. Her overall perception changes as she begins feeling that she’s always been sought out by others. Eventually, Farah becomes very popular among her current circle of people.

Counter-manifesting occurs when you redirect energy from an original manifestation to a new one.

For example, Justine craves the attention of her husband Jack but he’s usually very busy between work and spending time with his friends. She decides to manifest a life where Jack spends a lot of time with her. One day, Jack announces that he’s decided to retire. Justine is very excited and can’t wait to spend every moment with him. A few months pass and Justine realizes that she loves Jack but never has time for herself. She decides to fine tune and counter-manifest her wishes by manifesting a hobby for Jack. Soon afterwards, Jack joins a bowling league and Justine finally has the balance of time with him and time to herself that makes her happy.