The path to becoming a Security Guard in Delaware is unlike a lot of the other US states.
The difference is that there is no direct government application for a DE state Security Guard license.
A DE Security Guard is regulated through their Delaware security employer.
In DE, a Security Guard license application is an Employee Application.
This means your Delaware security employer will register you as a security guard with the state of Delaware via the regulatory body:
The Board of Examiners of Private Investigators and Private Security Agencies.