How do I remove Chinese characters appearing whenever I type？

The place to remove the Chinese input source is system settings / keyboard / text input / edit / all input sources. The minus button is at the very bottom of the window.

This happens because it's set as a text Input.

To fix it:

1. Open System Preferences
2. Go to Keyboard on the left panel
3. Scroll down until you see "Input Sources"
4. Click on "Edit..."
5. Remove all languages except the one that you want to type in (To remove click on the language and the click the minus (-) sign)
6. If you are not sure which ones to remove, remove all except U.S if you will be typing in English.