If you just wish it to be white, with the underlying artwork locked (in the Layers palette), you can give the lotus parts a white fill, either to the paths or with the Live Paint. You may also wish to know the Shape Builder.
If you wish whichever background is there to show through the lotus shape, you can:
1) With the underlying artwork locked (in the Layers palette), select the lotus shapes and Ctrl/Cmd+G to Group them (if not already), then Ctrl/Cmd+C+B to create a copy of the Group behind the original, then lock/hide the original Group in the Layers palette,
2) Pathfinder>Unite (or use the Shape Builder Tool) to turn the copy Group into a single path, then give the new path a black fill and no stroke,
3) Unlock the underlying artwork, select everything, then in the Transparency palette (flyout) click (Opacity) Mask with both Clip and Invert Mask unticked, then unlock the original lotus Group.