Richards said the restaurant had served over 3 million people over the past 20 years and the use of the slogan had only been questioned a few times.
"Fyi Monsoon Poon restaurant has been repeatively called out for using the racist phrase 'love you long time' in their marketing," one person wrote online.
"They have refused to stop using it. Feel free to Boycott Monsoon Poon. #givenothingtoracism."
Richards said she and co-owner Mike Egan were unaware of the name Monsoon Poon being a derogatory term and that the name was an "attempt to reflect the geography of the region as the monsoon is a unifying event for the area", reported Stuff.
"As there [were] other brands with just the word 'monsoon', we wanted to add to it, to make it unique and at the time, a Wellington chef named Ming Poon worked next door to us, and we thought his name would be a good fit, as they both end in a double o and n," they said.
"We were hoping he would come and work for us, but he went on to be the opening chef for Chow restaurant."
Concerns over the use of the slogan has been growing in recent weeks in the wake of a spate of anti-Asian hate crimes overseas.
On Twitter, one user said they were glad the "Love U Long Time" sign was going, but the restaurant's name was still "rascist and sexist" and "gross".
Monsoon Poon co-owner Egan said it was never the restaurant's intention to offend, "but when we looked into where this phrase had originated we agreed that it was time to remove it."
He said there were no plans to change the name of the restaurant.