You can block or unblock a number on an Android phone using the built-in Phone app's "Blocked numbers" menu.
Unless everyone is using iMessage, there's no way to remove yourself from a group text — you'll need to mute or block it.
Spam Calls: Almost every smartphone user in India faces spam and telemarketing calls daily. Spam Calls: Almost every smartphone user in India has to face spam and telemarketing calls on a daily basis.