(Reuters) - California teenagers, who post photographs of themselves wearing too little clothing or having had too much to drink, will have the legal right to erase their online indiscretions under newly enacted first-in-the-nation legislation.

The so-called 'eraser bill,' which Democratic Governor Jerry Brown signed into law on Monday, will require social media websites to allow California children under age 18 to remove their own postings as of January 2015, even as top sites already allow users to delete their own posts.

The law forces companies to provide a way for minors to delete digital skeletons - rants, postings and pictures that could harm their reputations, their chances of getting into college and their employment opportunities.

James Steyer, chief executive of Common Sense Media, a San Francisco group that pushed for the measure, called it a milestone and "a really important step forward in the discussion of kids and teen privacy....

"Kids and teens deserve the right to make mistakes without penalties for their entire lives," Steyer told Reuters. "This is the beginning of the reframing of the privacy issue when it comes to kids and teens, to let them control their own information and correct their mistakes."

While mainstream sites like Facebook and Twitter already allow users to delete posts, the law requires all social media sites to provide a delete button for minors.

Senate leader Darrell Steinberg, a Democrat who wrote the bill, said it protected children "who often act impetuously with postings of ill-advised pictures or messages before they think through the consequences.

"They deserve the right to remove this material that could haunt them for years to come," Steinberg said in a statement.

The California senate had unanimously approved the measure, which the state assembly approved 62-12.

Emma Llanso, policy counsel for the Center for Democracy and Technology, a group advocating internet freedom in Washington, D.C., praised the law for its good intentions, but said her organization opposes any age-based internet restrictions.

"This kind of bill could act as a disincentive to creating sites and services aimed at minors," she said, adding that her group fears that if other states adopt similar legislation, it could create a patchwork of laws that could prove difficult for technology companies to manage.

Steinberg said that a recent Kaplan study found that more than one out of four college-admissions officers check applicants' Facebook profiles and perform Google searches on candidates.

Steyer, the father of four children, including two teens, said he believes more work needs to be done to protect young people's online privacy. He hopes other states will follow California's lead.

"Just because you post a semi-naked picture of yourself at age 15 doesn't mean it should haunt you for the rest of your life or prevent you from getting into college, getting a job or ruin your reputation with your peers," he said.