How do I remove an old ADT system?

I have been a Simplisafe customer for nearly 3 months and LOVE it !! We installed it in a 4BR Single family home and it works like butter.

The previous owner had installed a wireless ADT (i.e. keypad, couple of motion sensors and entry sensors) system. I now have simplisafe and would like to get rid of the old system. I tried to pull the sensors but with it seems like that have been cemented to the walls and windows :-) Is it DIY project or do i need to call an ADT technician?

Has anyone encountered a similar situation before?


Hopefully the sensors are

Hopefully the sensors are screwed into the wall and removing the cover should show you this. Also you should unplug the phone line from the ADT box that should be in the basement or installed in a closet.