How to remove a virtualenv created by “pipenv run”

I am learning Python virtual environment. In one of my small projects I ran

pipenv run python myproject.py

and it created a virtualenv for me in C:\Users\USERNAME\.virtualenvs

I found it also created or modified some files under my project source code directory. I am just wondering how to cleanly delete this virtualenv and reverse my project back to a no-virtualenv state.

I am using python 3.6.4, and PyCharm.