Pan Pacific, which has run the site since 1995, was unavailable to comment on why the contract, which was up for renewal this year, will be pulled.
It is understood that an announcement will be made this week on who will take over the contract.
Despite the setback, Pan Pacific is continuing to expand in the country.
"We have had a great relationship with Ramaland Development the last 15 years and we wish them every success with the property," said Pan Pacific Hotels Group president A. Patrick Imbardelli.
"We will be strongly pursuing new opportunities for our brands in Bangkok and Thailand. We are confident of the long term prospects of this amazing country and it will not be long before we find that brand-defining and brand-relevant hotel for us."