If you want to prevent further growing you need to set your database logging to simple (but only if you do Full Backups of your database!).
- Right click on your database
- Choose Properties
- Choose Options
- Set Recovery mode to simple
This will work and is best if your backup schedule is Full Backup every day. Because in such scenario your log won't be trimmed and it will skyrocket.
If you would be using Grandfather&Father&Son backup technique. Which means Monthly Full backup, Weekly Full backup, and then every day incremental backup. Then for that you need Full Recovery Mode. So considering that you set your database to Full Backup you need to either stop doing that and switch backup to Simple Recovery Mode or start doing backups correctly and your log will be trimmed by backups.
In your case where you switch it to simple and then switch it to full your logs will grow again.
Combine this with as DanBig suggestion to Shrink the database by doing following steps:
- Open up Sql Management Studio
- Right click the database, Tasks > Shrink > Files.
- Under File Type, choose the the log file. Be sure to mark option
Release unused space as the shrink action, click OK.