PTT has suspended its football team PTT Rayong indefinitely, the state-owned company announced on Monday.
This means Suphanburi, who finished third from last in the 2019 Thai League 1 season, which ended Saturday, could remain in the top flight next year.
PTT Rayong will formally inform the Football Association of Thailand (FAT) of its decision on Tuesday, PTT CEO Chansin Treenuchagron told a press conference.
The FAT earlier said if PTT Rayong withdrew from the league, only two teams would go down to Thai League 2 -- bottom club Chiangmai and Chainat.
Chiang Rai United and Buriram ended up with identical 58 points from their 30 Thai League 1 matches. However, the Beetles were declared the winners of the league on the basis of a better head-to-head record.
PTT Rayong were 11th after losing 4-0 to True Bangkok United at True Stadium.
"We have decided to suspend PTT Rayong," Chansin said.
"This is because we want to support a youth academy instead. We have been playing our part in youth development projects in sports like football, futsal, tennis and swimming.
"There are two teams based in Rayong, but more importantly we don't have the needed expertise to manage a professional football club.
"We wanted to change our policy. Instead of managing a professional football team, we want to do a youth football academy.
"We want the young people from Rayong and other eastern provinces to have better football skills and we expect a positive feedback for the plan."
Chansin said the management board of the club had "no conflicts with anyone.
"Rayong has its local football team called Rayong FC and now that they have earned a promotion to the top division, we think people should support their own local team.
"As far as the contractual payments involving the team players and coaching staff are concerned, PTT will assume responsibility for these.
"We have not suspended the team because of any problems and that is the reason it has not been sold to any commercial entity.
"We have also agreed to use PTT Stadium as the training site for our academy in Rayong. We may also use it to host some youth competitions in the future."
At the end of Thai League 2 games on Sunday, the three teams to seal promotion are BG Pathum United, Police Tero and Rayong FC.
Meanwhile, Chonburi have granted a one-year contract extension to their coach Sasom Pobprasert.
Under Sasom, the Sharks managed to finish seventh in Thai League 1 this year. He took over as Chonburi coach shortly before the second leg kicked off in June and helped the eastern club secure 25 points from 17 matches.
Sasom said: "Chonburi have a distinguished history. They also have a good academy, some quality players and a loyal fanbase.
"I will try my best to bring more success to the team."