Thousands of German police vans are being deployed to the illegal tree houses in the Hambach Forest, where people have chained themselves over plans to clear the trees to expand the coal mining industry.
Authorities say the 30-60 make-shift dwellings there are unsafe.
The protesters have come to symbolize the resistance to the coal mining in the area.
Julia Brinner, supporter of "forest defenders", said: "This forest became a symbol. This occupation here has been six years so it has become a symbol for resistance against lignite for the fight for better climate."
Police clashed with activists during the week even though the protesters say it's a peaceful sit in, but local residents say it's been rather tense.
Erhard Nimtz, a local resident from Kerpen, said: "When we left the forest in a police car, suddenly two masked people attacked us by throwing Molotov cocktails at us. It was a very frightening experience for us."
The tree dwellers were given 30 minutes to evacuate the area on Thursday and they didn't resist and were removed by the police.
Cranes were used to reach people sitting in the trees. Authorities expect to take several days to clear the forest of people and the RWE energy company will start to clear the forest from the beginning of October.