How to stop Terminal from using special characters?

When I'm using arguments with quotes in the Terminal, the quote is first highlighted and then changes to a special character when certain characters are entered after it.

For example trying to type "u changes to ü.

How do I disable this?

I'm on OS X El Capitan, 10.11.6


Go to system prefs/keyboard/input sources and get rid of the layout called US International PC. Use US or ABC instead.