"The helicopter will go up there letter by letter," McDonald said.
There will be temporary street closures around the building, which is on South Broad Street between City Hall and Chestnut Street, from 6 a.m. till noon, said Streets Commissioner David J. Perri.
The helicopter will take the 12 letters and lower them down to the north side of City Hall, McDonald said.
One South Broad, as the building is known, is listed on the Philadelphia Register of Historic Places. It has been identified variously as 25, 26, and 28 stories tall. "On July 2, the Historical Commission approved the removal of this sign," McDonald said.
The permit was issued July 31, he said.
McDonald said he was aware only of the removal of the 12 letters and a steel structure supporting them. The tower also contains the 17-ton Founder's Bell in a belfry crown that is topped by the letters.
The sign survived several ownership changes. Philadelphia National Bank became CoreStates Bank, which was later bought by First Union. And then First Union merged with Wachovia.
In 2005, it was reported that Wachovia obtained city permission to remove the PNB letters, but the change did not take place.
The PNB letters have been a skyline fixture for six decades.
That will end Sunday morning.
The Philadelphia Business Journal reported in May that the building was purchased for $68 million by Aion Partners in New York in a venture with an unnamed insurance firm in Israel.
Michael Betancourt, an alumnus of St. Joseph's University, is a founding partner and managing director of Aion partners.
He could not be reached for comment.