How can I clean up the SSISDB?

 
Below are the Queries to clean SSIS DB. These are the internal tables that can be deleted.
 
USE SSISDB
    GO
    DELETE FROM [internal].[executions] 
    GO
    DELETE FROM [internal].[executable_statistics]
    GO
    DELETE FROM [internal].[execution_component_phases]
    GO
    DELETE FROM [internal].[execution_data_statistics] 
    GO
    DELETE FROM [internal].[execution_data_taps] 
    GO
    DELETE FROM [internal].[execution_parameter_values]
    GO
    DELETE FROM [internal].[execution_property_override_values]
    GO
    DELETE FROM [internal].[extended_operation_info]
    GO
    DELETE FROM [internal].[operation_messages]
    GO
    DELETE FROM [internal].[event_messages]
    GO
    DELETE FROM [internal].[event_message_context]
    GO
    DELETE FROM [internal].[operation_os_sys_info]
    GO
    DELETE FROM [internal].[operation_permissions]
    GO
    DELETE FROM [internal].[validations]
    GO