Hello mayadaibrahim,
Thanks for the help.
Well now that I see how tricky is Yoast with that, I will make sure that next time I want to optimize a slug for SEO purposes I modify it manually from my WordPress.
I do not have budget to purchase the Yoast Premium version because I do not even have traffic on my website, is there a way to fix that manually without paying for the Premium version?
Many thanks again.