Matthew Poole and continuators on Isaiah 26:14

14 They are dead, they shall not live; they are deceased, they shall not rise : therefore hast thou visited and destroyed them, and made all their memory to perish .

Those Tyrants and Enemies are utterly and irrecoverably destroyed, so as they shall never live or rise again to molest us. Possibly he speaks of the miraculous Destruction of Sennacherib's Army before Ierusalem.

That they might be so effectually destroyed, thou didst undertake the Work. Or, rather, because (as this Particle is used Numb. 14. 43. Psal. 42. 6.) thou hast, &c. as it follows.

Thou hast destroyed both them and theirs, and all the Monuments or Memorials of their Greatness and Glory.