You may have used a block or a repeating series of blocks in your agenda because you do not want your customers to be able to book during these periods. Do you want to delete a block like this?
This can be done quickly through your calender:
2. Double-click the block
4. Click "Delete"
Do you want to delete a whole series of repeating blocks?
2. Double-click on the block
4. Check the "Delete future blockeds" box
5. Click "Delete"
Now the entire series will be deleted from the block you double-clicked on.
Note: If you only have to remove a few blocks from the whole series of blocks, then do not check the "remove future blocks" check box.