Hong Kong bailiffs are clearing out a protest site near government offices after the high court granted an injunction authorising the move.
The bailiffs, accompanied by police officers, are removing barricades at Citic Tower in the Admiralty area.
Pro-democracy student protesters have begun packing up their tents to move elsewhere. The court order covers only part of the site.
The high court has also authorised the clearance of the Mong Kok site.
A third protest camp remains at Causeway Bay.
The BBC's Karishma Vaswani in Hong Kong said the scene at Admiralty appeared calm, with many students saying they would not get in the way.
Prominent student leader Joshua Wong told the BBC that they would not resist as long as the authorities only cleared the area mentioned in the injunction. Mr Wong said if the authorities headed to other sites, activists would be "very disappointed".
Protesters at Admiralty have said they will simply move elsewhere. Garment worker Jason Fung told the South China Morning Post: "We'll just go protest somewhere that the injunction doesn't cover."
Last week the Hong Kong high court granted an injunction to the owners of Citic Tower to clear access to the building.
It has also granted an injunction to taxi and minibus associations to clear the roads in Mong Kok, where on Tuesday protesters had also begun packing up.
More requests have been lodged by bus companies to clear other roads affected by the protest sites.
Police attempts to clear and contain the sites in recent weeks have sometimes led to violence. An attempt to clear an underpass near Admiralty led to accusations that the police used excessive violence, after a video emerged of officers apparently beating a protester.
Protesters at Admiralty have been packing up as bailiffs move in to clear part of the site
The protests in Hong Kong have lasted for nearly two months. Demonstrators are calling for the public's right to nominate candidates in the 2017 chief executive election, following China's decision to screen candidates.
At their peak, the protest drew tens of thousands of supporters to the streets. A few hundred protesters, many of them students, have remained at the three protest sites in organised tent cities.
An attempt by student leaders to travel to Beijing to seek an audience with Chinese Premier Li Keqiang failed at the weekend, after their travel permits were declared invalid.
Hong Kong democracy timeline
1984: Britain and China sign an agreement where Hong Kong is guaranteed "a high degree of autonomy, except in foreign and defence affairs" for 50 years following the handover in 1997.
June-July 2014: Pro-democracy activists hold an unofficial referendum on political reform and a large rally. This is followed by protests by pro-Beijing activists.
31 August 2014: China says it will allow direct elections in 2017, but voters will only be able to choose from a list of pre-approved candidates. Activists stage protests.
22 September 2014: Student groups launch a week-long boycott of classes in protest.
28 September 2014: Occupy Central and student protests join forces and take over central Hong Kong.
October 2014: Chief Executive CY Leung refuses demands for his resignation. Discussions between government and student leaders go nowhere. High court begins granting injunctions to clear protest sites.
15 November 2014: Student leaders' attempt to travel to Beijing fails.
18 November 2014: Bailiffs move in to clear a portion of the Admiralty protest site.
2017: Direct elections for chief executive due to take place
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