There are almost 8000 city in this country (it is not so big), but I can't reduce it because is a normal job ads for all city in this country.
The only real problem is that client freeze when selecting job location, can be resolved in some way?
I do not understand when you say "why you can disable Employer to add job location ?", the installation of wp and theme is fresh and most of configurations are set at default. I have do it, but in searchbox there are no changes.