Within the Employees & Users area of Core iQ, you can turn off all dashboard charts for certain employees. Simply navigate to the employee's profile and ensure that they do not have any Roles checked on their Roles section. These Dashboard charts are actually influenced by what roles are assigned to that employee, so if they have no roles, they have no charts. The only Role that doesn't influence charts is the Compliance Role, which is used to determine whether the employee can Approve templates to send in Core iQ.
You will also want to ensure that the Can Change Dashboard Preferences option is set to NO. With this feature enabled, they will be able to add and modify the charts that are present on their Dashboard. To explore this option more, check out our How to Configure Your Core iQ Dashboard article.