If all is SAME one title, then ALL need to agree in writing,
BUT if the property is splited into own shares, then can everyone do as they want with their share.
If it isn't splited yet, then they, who want to sell, have right to FORCE the legal spliting process steps.
But I hope they, who want to sell, give the one, who want to keep, the chance to buy whole for a decent price. If one buy out the others is the process some less complicated, because then the title don't need to be splited, but the inherit process is needed anyway to be sure to avoid problems in the future.