I have a Mac book pro I was trying to erase and now have a blinking question mark folder and cannot get it off the screen after turning it on and off. Any advice?

Assuming there are no physical/hardware problems with your Mac, you need to do it again.

Here's the procedure for erasing: How to create a bootable installer for macOS - Apple Support

It's starts by describing how to make a bootable drive and then at the end how to use that drive to install the OS of choice. Follow the applicable points precisely.

If your Mac starts up to a question mark - Apple Support

Hi,

Following document could help your question.

How to reinstall macOS - Apple Support

If it doesn't help, take your MacBook Pro to your local retail AppleStore, Genius Bar or Apple Authorized Service Provider to install macOS on your MacBook Pro. As far as I know, it's free.

Genius Bar Reservation and Apple Support Options - Apple

https://locate.apple.com/

You seemingly did erase that Mac, as that ? means there’s nothing available to boot.

Assuming a not-old Mac, boot recovery: Erase and reinstall macOS - Apple Support