Your SQL Log File is basically your lifeline when it comes to recovering your database to a previous point in time. If Point in time recovery is not important to you; then you must set the Recovery Model to Simple.

To deal with the issue in hand; lets go through a series of simple steps to shrink your log file

1. In the Query window, type;  backup log <databasename> with truncate_only
2. dbcc shrinkfile (databasename_log)
3. Once this is done; you will noticed your log file having shrinked considerably within your file directory

If Point in Time recovery is useful to you; I would recommened that you schedule the above activity periodically to keep the size of your log file in check.