Can a single rotten board be removed and replaced

if a board is rotten it means the roof is leaking not necessarily where the rotten board is as water will generally travel to the lowest point, to access the board you will need to remove the covering to asses and access the damaged board without removing the roof covering you have no way of knowing how much damage there is , you will then need a clean surface to attach your new roof covering to free from dirt ,so in short if you want the job done properly no its not possible to only remove 1 board. good luck Alex

Of course the board can be removed. Unless its in a valley, against a hip or under a ridge. Just remove tiles to affected area and replace board. Simples