The events that have been added can be updated at any point in time. This can be done as: Events -> Manage events

On this page, a list of all the events that have been added would be visible. Any event can be selected to be edited. Click on green 'pencil' icon to update the events.

On this page, various event details would be visible that can be edited. Please note that everything can be edited on this page except event hashtag.