WordPress appends the “-2” to a slug
WordPress appends the “- 2 ” to a slug you still have the old content by the same name, probably in the trash, draft, etc. If so, try emptying it or check media section there must be some image with the same name like I was having problem for cloudhostweb.com/vps there was image cloudhostweb.com/vps.jpeg I had deleted the image and it worked perfectly