Dump your log file into oblivion, then do a full backup to maintain a safety net... Add a new log file that has an appropriate size to your database, and empty the existing log file into it. Drop the empty log file that you just evacuated. I recommend doing a second full backup at this point, even though it isn't strictly necessary. At this point you've restored sanity to your database files.
Logging can NEVER be turned off while SQL Server is running (except if the database is made read-only). Logging can be minimized, but there is no way to completely stop logging for a functional database.
The SIMPLE recovery mode will allow the CHECKPOINT to clear unused log rows. This is usually fine on a development database, but I don't recommend it on either QA or production databases.