How to remove green from roof tiles?

How to remove green from roof tiles?

Bostik Green Remover is suitable for external roofs. Remove loose material and heavy surface growth first, then test on a small, concealed area. Apply the correctly diluted solution in dry weather, leave it to work without rinsing and allow 1 to 5 days for the green staining to loosen. For severe growth, a second application may be needed after 24 hours.