search and delete select sms? I get all these spam sms from everywhere...

I tried the phone's usual search feature. I search for a spam keyword in my messages, and then try to delete all those messages. 

The problem here is that I don't have the option to select all those messages at once and delete them; instead I've to manually delete those messages. 

Is there a better way to manage this problem?
SMS Search and Delete have option to select all found messages and delete  them all at once.