Please use the commands below:
"C:\Users\Grace Wu\torchenv\python.exe" -m pip uninstall torch torchvision
"C:\Users\Grace Wu\torchenv\python.exe" -m pip install torch==1.5.0+cpu torchvision==0.6.0+cpu -f https://download.pytorch.org/whl/torch_stable.html

If it doesn’t work, then please manually remove the DLLs in C:\Users\Grace Wu\torchenv\lib\site-packages\torch\lib after you uninstall PyTorch.