Open Viber
Go to the chat with the person you want to block
Tap the person’s name or profile at the top
Tap Block
Confirm by tapping Block again
Open Viber
Go to More
Tap Settings
Tap Privacy
Tap Block List
Tap Add Number
Enter the phone number or select a contact
Tap Block
On Android, open the chat
Tap the three dots
Tap Chat info
Tap Block this contact
Confirm the block
On iPhone, open the chat
Tap the contact name
Tap Info
Tap Block this contact
Confirm the block