The building was gutted by fire in February.
Phase one of demolition works involves a process of initial site forensics and the design and implementation of a traffic management system.
Managing director John McAuliffe said: “The speed of demolition is critical to the rebuild, but demolition works of this scale also takes time and planning to ensure that work can progress safely and uninterrupted, but with the absolute minimum local disruption.
“We’ve got some pretty big machinery on-site, with some weighing in at over 55 tons, to tackle the mangled steelwork, but some elements required careful dismantling, removal and storage for investigation in relation to the cause of the fire.”
Carvers Building Supplies will rebuild on the site once demolition is complete.
Henry Carver, Managing Director of Carver Building Supplies said: “It’s heart-breaking to see the site in this state, but we are determined to rebuild the business and the demolition works is a good first step.”