how to restrict a particular user from deleting records of a specified entity

Hi All,

I have a requirement to restirct users having sales rep as their security role from deleting some records. We have a customized entity called as "areas" in which we have some associated entities like city and province. We need to restrict sales rep from deleting records of these associated entities like city and province on areas form page. 

Thanks in advance!

Regards,

Vijetha