Messi leaves Barcelona after the side failed to provide him a new contract under LaLiga's salary limit despite a private equity firm ready to invest in the LaLiga which would have seen Barcelona giving up some TV rights.
And indicating the consequences of maintaining the 34-year-old, Joan Laporta said;
"I can't make a decision that will affect the club for 50 years," Laporta said.
"The club is over 100 years old and it's above everyone and everything, even above the best player of the world. We will always thank him for everything he's done for us.
"In order to have fair play, we need to do this or make an effort which would put the club at risk. We couldn't keep going with this and we needed to make a decision, which we have.
"Leo wanted to stay, so he's not happy," Laporta said.
"We all wanted him to stay. For him, he has to confront reality. It's a reality that can't be changed and he knows I wish him the best wherever he goes.
"Leo's legacy is excellent. He's made history," Laporta said. "He's the player with the most success in history of the club.
"He's been the reference of an era which has been splendid. The best era of Barca's history until today.
"A new era starts now. There will be a before and after Leo. We need to be eternally thankful to him."
Lionel Messi has left as a free agent with PSG and Manchester City being the favourites to land the services of the 34-year-old.
The Argentine currently holds Barcelona's record scorer with 672 goals and has won 10 La Liga titles, four Champions Leagues, seven Copa del Rey trophies, including six Ballon d'Or glories.