Yes.
By default, Lockers are undeletable on the computer where Folder Lock is installed.
However, you can delete Lockers from within the application. In 'Encrypt Files' there is a button called 'Delete' that asks you the Locker password when you wish to delete a particular Locker from the list.
If you do not want to keep your Lockers undeletable, you can do so by going into the 'Security Settings > Password Security' and uncheck the option for it. Note: You will require a Master Password if you enable Locker Delete Protection in Settings>Password Security.