Cannot delete customers and vendors


i was trying to delete customers and vendors, but got a strange error. Saying that i don’t have permission to execute “Service Item” table. I used developer license, does anybody know how to solve the issue?. My nav info:

NAV 2017 - 10.0.17972


First go to Table 5940 service item and then delete all the transactions in there and then try to delete customer and vendor and it should work.