1. Go to your database in Management Studio.
2. Right click on the database and select Tasks -> Backup. Choose Transaction Log as Backup type.
3. When backup is taken, right click on database, select Tasks -> Shrink -> Files. Choose File type Log.
In 95% of cases that will do the trick.
Cannot shrink log file 2 because the logical log file located at the end of the file is in use.
Then you need some extra steps.
2a. Right-click your database and select Properties. At Options tab set Recovery model to Simple.
Do Step 3.
3a. Set recovery model back to Full.