When you click on a room that has a scheduled closure, you'll see all of the dates that the room is currently closed for. You can also view the closure by finding it on the Grid and selecting it. To make any changes, click Edit closure. Past closures are still visible on the grid, but you won't be able to edit them.

When you click on one of those dates, you'll be able to edit that particular closure. You can remove rooms, edit the dates and edit the descriptions easily from here.

To cancel the closure, press Delete closure. If you have a multiple room closure, and you just want to remove one of the rooms, press Remove this room (it's next to 2nd Room and onwards).