To block a friend from exchanging messages with you, tap the
friend in the chatting list. Tap the Menu icon (at the upper-right corner of
the screen) > People & options. Tap the
block icon
next to the
friend's name, then tap BLOCK.
To remove a friend from the blocked list, from the chatting
list, tap the Menu icon (at the upper-right corner of
the screen). Tap Blocked people, then tap the
blocked friend. Tap Unblock at the top of the
screen.