Changing a Business Event Date 
...
1. On the SAP Easy Access screen, in the SAP Standard Menu choose Human Resources ® Training and Event Management ® Business Events ® Dates ® Change.
2. Enter the Business event you want to change.
3.
Choose
data
screen.

It is even easier to call this function from the dynamic Business Event Menu. There you simply select the event date you want to change and choose Change with the right mouse button.
4. Change data as required.
If you want to change the business event schedule, proceed as described in Create Schedule

If you want to change or add to the resources selected for a business event, refer to: Selecting Resources
5.
Choose
.
You have changed the business event date.

Please bear in mind that you should only use the transactions of Training and Event Management (e.g. PV1A, PSV2) for editing business event dates and not transaction PP01 to avoid data inconsistencies occurring.