You can do so in 2 ways:
1. Through UMB by dialling *500*31# and selecting menu option 4. Stop subscription
2. By sending an SMS in the format:
- UNREG(space)melo30 if you are on 30-day subscription.
- UNREG(space)melo15 if you are on 15-day subscription.
- UNREG(space)melo7 if you are on 7-day subscription.
- UNREG(space)melo3 if you are on 3-day subscription.