Honestly, I think you should fire him, or the other 4 employees. At your stage, you can't be distracted by this kind of issues. You should also review your hir

Honestly, I think you should fire him, or the other 4 employees. At your stage, you can't be distracted by this kind of issues. You should also review your hiring process and see how you can avoid this in the future, I can guess that you interviewed the technical people, and your CEO the non-technical ones, and you (together) didn't catch this as a potential issue.