Angela Villela Chavez did so with prejudice, meaning she is prevented from refiling the case.
She now says she regrets her decision to choose Lisa Bloom as her attorney.
Bloom told the judge she was forced to withdraw from the case for ethical reasons.
Chavez had accused Cardenas of molesting her in 2007, when she was a rising junior golfer.
The San Fernando Valley Democrat had vigorously denied the allegations.
Cardenas says "the truth prevailed," thanking his family and constituents.