Do you leave dotenv file in the server? Or delete it?

I'm building a flask application and use dotenv file to switch some variables up to environment, such as production, development, and testing.

AFAIK dotenv is mainly used for security purpose, so should I delete dotenv file from the server once I started to run the application?
If so, when the application is down I would need to pull the dotenv from somewhere, re-run the application, and then delete the file again.

It's not likely to be a good idea to leave dotenv file in the server,
but the above sounds a little bit annoying from an operation perspective.

What is the best practice?