The protesters cut themselves free around 10pm after City of London Police entered the cathedral, an occupy spokesman said.
He said they decided to cut themselves free after being warned by officers that they faced arrest.
They have now left the cathedral.
Some of the awareness-raising they wanted to do has been done.
The Dean has also agreed to meet them and talk.
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Sadly, these high-school students have already received the most abrupt and cynical lesson of their lives.
A top temperature of 9 or 10 Celsius (48-50 F).
The poll comes ahead of a debate in the House of Commons on Friday on a new Bill which would introduce such a system in England.