How to unluck security system of cadilac devlle 2001..my key wont get in to the ignition

The key switch may be drilled out but the ignition switch may not be ingageing the power it needs for the electrical system ,replace the key cylinder .

There isn't one. The 2000 DTS has a VATS security system. The car has to have the right key in the ignition for the system to turn on the fuel pump and the ignition system. Without those, the car no run.

Turn the key to acc and wait about 10 minuter for the security light to go solid or stop blinking

The antitheft or lock picture/icon is a visual indication that something in the car's antitheft system is failing. In most GM cars and trucks there is a hidden system that most people are unaware even exists. From the moment you put your key in the ignition, there begins a constant line of communication between your key's security chip or transponder, to the ignition's lock cylinder, and then to the car's TDM (Theft Deterrent Module). These 3 parts are in CONSTANT communication. If the key is in the ignition, then these parts are sending signals to each other. The security light illuminates when that signal gets broken, even just for a second. When the signal breaks, the car misinterprets this as an attempt at theft and goes into antitheft mode. The car thinks its being stolen or hotwired because it is not getting that signal from YOUR specific key. This is why the security light turns on and shuts down your vehicle. This link explains it pretty well.
http://vatspasslockpasskeysecurityhelp.yolasite.com/

The theft or lock icon is a visual indication that something in the car's antitheft system is failing. In most GM cars and trucks there is a hidden system that most people are unaware even exists. From the moment you put your key in the ignition, there begins a constant line of communication between your key's security chip or transponder, to the ignition's lock cylinder, and then to the car's TDM (Theft Deterrent Module). These 3 parts are in CONSTANT communication. If the key is in the ignition, then these parts are sending signals to each other. The security light illuminates when that signal gets broken, even just for a second. When the signal breaks, the car misinterprets this as an attempt at theft and goes into antitheft mode. The car thinks its being stolen or hotwired because it is not getting that signal from YOUR specific key. This is why the security light turns on and shuts down your vehicle. This link explains it pretty well.
http://vatspasslockpasskeysecurityhelp.yolasite.com/

The security light is a visual indication that something in the car's antitheft system is failing. In most GM cars and trucks there is a hidden system that most people are unaware even exists. From the moment you put your key in the ignition, there begins a constant line of communication between your key's security chip or transponder, to the ignition's lock cylinder, and then to the car's TDM (Theft Deterrent Module). These 3 parts are in CONSTANT communication. If the key is in the ignition, then these parts are sending signals to each other. The security light illuminates when that signal gets broken, even just for a second. When the signal breaks, the car misinterprets this as an attempt at theft and goes into antitheft mode. The car thinks its being stolen or hotwired because it is not getting that signal from YOUR specific key. This is why the security light turns on and shuts down your vehicle. This link explains it pretty well.
http://vatspasslockpasskeysecurityhelp.yolasite.com/

can you put the broken key into ignition barrel up and turn

It may be as simple as trying a different key but the security systems on gm vehicles have had problems with the ignition cylinders going bad and preventing the car from starting.

when security light comes on your car is in theft mode.you can try another key.if engine still dont crank.dealership have to fix it.they have check the ignition switch and.pcm theft detterrant system.also cars keys have a chip on it.they have to check to see if pcm is reading the keys.if not they have to replace ignition switch and keys and reprogram your pcm theft deterrant system.so your car will crank.

Most likely there you have a security system VAT (Vehicle Anti-Theft) module. If you try to bypass this the car will not start. Have a mechanic or yourself get to the main wiring harness to the ignition in the steering column under the dash, unplug it and use another ignition with a key in it to learn the security system code first before trying to start it.