The Prophet ﷺ said, "Whoever manumits his share o a jointly possessed slave, it is imperative on him to manumit the slave completely if he has sufficient money to pay the rest of its price which is to be estimated justly. He should pay his partners their shares and release him (the freed one).

عَنِ النَّبِيِّ ﷺ قَالَ مَنْ أَعْتَقَ شِرْكًا لَهُ فِي مَمْلُوكٍ وَجَبَ عَلَيْهِ أَنْ يُعْتِقَ كُلَّهُ إِنْ كَانَ لَهُ مَالٌ قَدْرَ ثَمَنِهِ يُقَامُ قِيمَةَ عَدْلٍ وَيُعْطَى شُرَكَاؤُهُ حِصَّتَهُمْ وَيُخَلَّى سَبِيلُ الْمُعْتَقِ