Very easy!
First, go to the Project Administration of your target project to remove the option.
Then, go to the Field Configuration ( all of them if there are more than one).
Edit the “description” of the “description” field ( or some customfield that is visible in the project screens).
Add this “javascript” code in HTML in the “description” of the field.
<sctipt>jQuery('#clone-issue').remove();</script>
That’s all!
