Delete Rows - ClearAll()

I need delete all the rows and keep the headers of the grid, I try to use the clearAll() function but this delete also the headers. There is a way to delete all the rows in the grid but keeping the grid structure?

grid.clearAll can be used for both tasks

gridl.clearAll() - delete data, but headers and settings untouched
grid.clearAll(true) - delete all, including headers