Ambulance staff had earlier attended the scene and discovered the man, who is thought to be a local in the town.
The victim has not been formally identified but his next of kin have been informed, a spokesperson for Devon and Cornwall police said.
Following the grim discovery, police arrested the 21-year-old man at the scene and two 17-year-olds were arrested shortly afterwards.
The two youths, who have not been named, have now been released without charge.
The 21-year-old man will appear before magistrates this morning, Devon and Cornwall police added.
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