How to disable option key to type greek letter in Mac OS?

I use Ukulele to fix this issue.

1. Set current input Sources to U.S.
2. [Menu] File->New from current source
3. Pressing Option+a/b/c.... and double click the highlight key, clear the content.
4. [Menu] Keyboard->Set Keyboard Name save as a new name, set the format to Keyboard layout file.
5. Click 'File'==>'install' or, Copy the layout file to /Library/Keyboard Layouts
6. Open Keyboard Preferences, click Others, select your custom layout.

This is my settings looks like, you can delete them all.

That all, Now you can use emacs key style in some IDE such as IntelliJ or Android Studio.

Solved natively as follows:

⟶ System preferences
⟶ Keyboard
⟶ Input Sources Tab
⟶ + at bottom left
⟶ add and select Unicode Hex Input

 ✓  Mac no longer prints anything on alt+letter|number
 ✓  entered unicode characters via alt+[code]
 ✓ Keyboard shortcuts are assignable to alt key

I know it's an old question, but i found a easy solution.

In Mac 10.14.4, there is a input source called "Unicode Hex Input", this will disable the option key for special letter.