The simple straight forward method to truncate logs in the occasion where you find yourself running out of disk space and do not have additional free space to spare.
Open SQL Studio > Select the database in question > Right click and Select Properties
From the Database Properties Window select Option and change the Recovery model to Simple.
Then Right click the database and select Tasks > Shrink > Files. Change the File Type to Log > Select OK
This will truncate the .ldf file.