How to remove that Exclamation mark in message icon ?

Hello bharathi291,

Thanks for choosing the Apple Support Communities. This is an indication that a messages failed to send. If you open the Messages app and see that all messages have successfully sent, let's try these steps to resolve the issue.

1. Close the Messages app and re-open - Close an app on your iPhone or iPod touch - Apple Support
2. Restart your iPhone - Restart your iPhone - Apple Support
3. Force restart your iPhone - Force restart iPhone - Apple Support

Give those a try, and let us know if they help.

Cheers!