To block beds you can simply select beds on Bed View, right-click the selected beds and click on Block Beds:
To unblock beds you can simply select block beds, use the right-click to show the menu and select Unblock Beds.
If you click on one bed only, you will see two options: one to unblock only this one bed and second, to unblock all previously blocked beds.
If you want to block more beds, it is very easy when you click the red icon on top of the Bed View to access the Block & Unblock Beds window. You can select the days, rooms and beds and run BLOCK or UNBLOCK command.