Delta marketing and communications manager Amelia Currier said the buildings were bought from the Dunedin City Council in June 2011 as part of a package which included Delta's office building and yard.
At the same time, the land the buildings are on was bought from Port Otago subsidiary Chalmers Property.
"Since acquiring these particular buildings, Delta has used them largely for storage purposes," she said.
Once demolition was completed this month, the levelled area would be gravelled, the perimeter fenced, and Delta would use the space to store plant and equipment.
This work was part of a wider Delta initiative to improve its facilities, including resurfacing of the depot's asphalt, installation of electronic gates and a cafeteria.
Ms Currier said Delta had teamed up with a local artist, and the Dunedin Street Art trust, to bring some colour and creativity to two of the outward facing walls.
The red-roofed buildings behind the demolition site are a substation, the second built in Dunedin, between 1937-39, in Bauchop St, which is operated by Dunedin City Council-owned company Aurora.
