Todd Property said the demolition work was being carried out by a contractor using a 68-tonne long-reach excavator with a pulveriser head and would involve the concrete structure being "gradually nibbled away from the top down".
Between 4-6 workers are expected to be involved in the demolition process, which will take about five months.
"We know the community has a strong interest in this project, given the historic importance of the site and the buildings to the people of Napier and the Hawke's Bay," Todd Property managing director Evan Davies said.
"We are committed to producing a high-quality development at Napier Hill that reflects its unique nature with its prominent city location and stunning views."
Mr Davies said the company's focus since receiving consent had been on fully clearing the site, including the land at the eastern end where the tower block is located.
This had resulted in a delay starting the Arohaina apartment construction.
"We have already sold a number of sections for standalone homes at Napier Hill and are excited to see that future residents are well under way with their designing and consenting processes," Mr Davies said.
"We have had some interest in Arohaina Apartments, which was due to be the next stage of the development.
However, we have decided to defer construction for the time being and reconsider dates for the project later in the year."
