env | grep -i proxy is just that: a command. All this command does is produce some output. In this case, the output tells you which environment variables are set where either the name or the value of the variable contain the string
vim is a text editor. It is used to edit (text) files. You're trying to use a text editor to edit terminal output, which doesn't make sense in the first place, and even if you edited the terminal output, it wouldn't change the fact that these variables are still set. If you want to permanently unset some environment variables, editing terminal output is not the way to go.
What you want to do is find out how and where these environment variables are being set. Presumably, you have a few lines in you
~/.bashrc (assuming you are using bash) or
~/.profile files that set these variables at the start of a session. You can use
vim to edit these files like so:
Search for lines that look like
and remove them.
Please be aware that
vim is a rather advanced editor that is not necessarily intuitive to use. If you have not used
vim before, I would suggest you use another editor for such a simple task, such as
nano, which comes preinstalled with Ubuntu: