毁你如何
[huĭ nĭ rú hé]
The user name 'Ruin you, how?' seems aggressive. It can either mean to express a strong resentment toward somebody, questioning the ways to bring them down, or it can serve as an indirect self-mockery showing a certain self-deprecating confidence or sarcasm. Without more context it's tough to tell which meaning the username intends to emphasize.