Authorization 
What a user is allowed to do with work center data depends on the authorizations he has been given in the user master record:
- Activity authorization allows the user to create, edit, display and delete work centers.
- Work center category authorization allows a user to maintain a particular work center category.
- Plant authorization allows a user to maintain all work centers in a particular plant.
Your system administration is responsible for authorizations. For further information about users and authorizations see the R/3 Library BC Basis