The great Facebook friend cull is now well established, with more than half a billion people "defriended" last year alone.

But a delicate question remains - how do you delete the third cousin you met at a wedding two years ago, your former flame or historic co-worker without the unwanted friends taking offence?

Some suggest making a status along the lines of: "If you're reading this, you've survived the annual friend cull. Congratulations."

Others prefer to sneakily delete people because they know it won't be until they try to visit your profile that they realise you didn't want to be their cyber friend any more.


Ros Ellwood has her own rule for keeping her friends list intimate.

"If I wouldn't stop and talk to them in the street and have a conversation, I wouldn't have them as a friend on Facebook."

The Dunedin recruitment consultant keeps her friends list to 100 and under - she's just recently added her friend's boyfriend which has bumped her number up to 101 so she is now deciding which person to cut.

It gives the 32-year-old control over who sees what and who is allowed to pry into her private life.

"You sometimes see these people with thousands of friends and you think, 'Would you even recognise them or talk to them.' It horrifies me to think of sharing all my personal information with that many people," she said.

According to research conducted in the United States last year, the number of people defriending other Facebook members rose from 56 per cent in 2009 to 63 per cent in 2011.

More than a half a billion people were culled.

The study by the Pew Research Centre's internet and American Life Project also found that 67 per cent of women on Facebook said they had deleted friends compared with 58 per cent of men.

Women also tended to choose much more selective privacy settings.

Ms Ellwood has hers set so people can't find her by searching her name.

"I work with a lot of people and you don't really want them typing your name into Facebook and finding you and seeing photos of you out in the town on Saturday night."

She hides posts in her news feed from Facebook friends who make inane comments about weight loss.

As a seasoned defriender, Ms Ellwood said there was no polite way of removing someone from your profile.

Only once has she had backlash.

"I deleted someone due to a bit of an incident with an ex-boyfriend of mine who seemed to be finding out a lot of information about me and could only work out it was coming from the wife of a friend of his.

"So I deleted her and I got a big email saying, 'I know what you think's been happening, but I'm really sorry - please take me back,' which I did. It was just a big misunderstanding."