1. Database-> Properties-> Options-> Failure Recovery Model changed to Simple
When I changed, there was a prompt saying that the database log or something, I did not see clearly
Then in the second step, the "shrink database" is grayed out.
Under program files\mssql\data are all data and log files. Each database has 2 files, one is a data file and the other is a log file. Just look at the extension and you can delete the log file.