The 30-year-old singer-actress left the centre just one week after she entered an in-patient treatment facility - seeking help for anxiety and stress, reported Femalefirst online.
Rimes is taking a break from the course, which was supposed to last 30 days.
"I'm on a plane headed to see all my fans in Wisconsin tonight! I'm so ready. I've got a zillion fashion mags, my journal, iPod, water and a butterfingers. I'm all set," she posted on her blog.
Following her decision to get help, her representative said she was merely in rehabilitation to "learn and develop coping mechanisms" for stressful situations.
However a source close to Rimes and her husband, Eddie Cibrian, said that her main source of anxiety is a preoccupation with thinking her spouse will cheat on her.
"LeAnn has had major insecurity issues since she first got together with Eddie. She's been stressed about always being called a home-wrecker and also worried that Eddie is cheating on her. She's been on a downward spiral," a source said.