Why did Lin Beixing cross back?

In the play, 30-year-old Lin Beixing was betrayed by her boyfriend and best friend, and her depression affected her life and work. She finally decided to delete the memories related to her boyfriend and start a new life, but when she deleted the text messages from her old mobile phone, she triggered the time-space gear and returned to high school.

This shows that only by deleting the SMS of the old mobile phone can we go back to the past.