-bash: /usr/local/bin/nmap: Bad CPU type in executable
I decided to go the site : 

https://nmap.org/book/inst-macosx.html



Click on Download

https://nmap.org/dist/nmap-7.80.dmg

I downloaded that .dmg, installed it, now my nmap working again. 




  Note : I will leave this post since, it might help others in the future.