We theoretically investigate a wavelength-selective all-optical switch using Raman-induced loss in a silicon resonator add-drop filter. We show that picojoule control pulses can selectively modulate and "erase" a single cavity resonance from full extinction to greater than 97% transmission while leaving adjacent resonances undisturbed. Full switching is achievable in less than 300 ps with only a few hundred femtojoule energy dissipation. This represents, to our knowledge, the first scheme for selective modulation of single resonances of an optical cavity.