If the price you want to delete is a discount in one of your price list zones (eg the student in the example below), you can delete it as follows:
Click on "in detail" in the zone the dicount belongs (column "discounts")
Select the discount and
Click on "delete".
Attention:
Deleting the entire zone or price list is not enabled.
You can however, not assign tickets to a price zone you don't want to use.
In the example below, if we don't assign any tickets to Zone B, only Zone A will appear on the ticket sales page.