Complex sentence: Professors who have turned 70 are required to leave their positions, but may continue to use the title (or professor emeritus/emerita) and in some cases may keep their office and access to university infrastructure as long as they are still active as researchers.
Split into simpler sentences: Professors who have turned 70 are required to leave their positions, but retain the title. In some cases may keep their office and access to university infrastructure as long as they are still active as researchers.