The QE2 will no longer bear the name of its former home port Southampton.
The city's name has been replaced with the liner's temporary home port of Port Vila by its new owners, United Arab Emirates real estate developer Nakheel.
Cunard sold the ship for £50m to Nakheel, which is now in talks to move it to Cape Town to become a hotel in time for the 2010 football World Cup.
The developer said international law required the removal of Southampton since it was now registered in Vanuatu.
The QE2 left the Drydocks World-Dubai, where it was transferred to in July for routine marine surveys in compliance with international standards, last Saturday in preparation for sea trials.
A spokesman for Nakheel said: "Although she will no longer be taking passengers or operating as a cruise ship, the registration documents will state her class as being 'a passenger/cruise ship'.
"To conform to international law, the name 'Southampton' has been painted over on the stern, although the letters remain attached, and her temporary home port of Port Vila has now been painted underneath.
"To comply with the terms of the sale contract, the Cunard brand has also been removed from the side of the ship."
Nakheel had planned to refurbish the ship and open it as a floating hotel in Dubai but that has been put on hold.
The QE2 will now go to the Victoria and Alfred Waterfront in Cape Town, where there is a shortage of hotel rooms.
Nakheel, which has a financial interest in the South African port, said the ship would be staying in Cape Town for 18 months.