The correct way to remove parametrisations (this or any nn.utils.parametrizations) is through torch.nn.utils.remove_parametrization: torch.nn.utils.parametrizations.spectral_norm — PyTorch 1.10.0 documentation 1
As a side note, all this is documented in the parametrizations tutorial: Parametrizations Tutorial — PyTorch Tutorials 1.10.0+cu102 documentation 2