Free up space
Just downgraded my macbook pro from mac os catalina to mac os mojave. Before downgrading, took a backup on time machine. Now after downgrading, system is showing just 22GB free out of 500 GB, whereas only 12GB is used space. Nothing else on the system. I am not able to take backup due to lack of space. What needs t be done here?
MacBook Pro 13", macOS 10.15