Custom entry types can be hidden in the Admin section. Once hidden, the entry type will no longer be displayed as an option.
Go to the Admin section and click Calendar Entry Types.
Right-click your custom entry and click Hide.
Awesome. This entry type will no longer be available for use.
If you want to unhide a custom entry type, that’s easy, too.
Right-click your entry and select Unhide.
Ta-da! Your custom entry type is now unhidden.