How to reduce LOG file after switching from full recovery mode to simple mode? I have a database with full recovery model and without TLog backup. 

The log file have grown to 160GB and I found out that it needs TLog to be periodically backed up or the recovery model switched to simple. Now that I have switched to simple recovery model, the .ldf file is still of the same size. 

How can I reduce it?
You need to perform a shrink operation on the log file.

You can follow the instructions there.

PS: Don't forget to switch back to FULL Mode.