For Android
1. From the Home screen, tap Phone > Tap More (3 dots) >Tap Settings / Call Settings.
2. Tap Call blocking (if shown) > Tap Block list / Block numbers.
3. Tap the minus sign next to the numbers.
For iPhone
1. Go to Settings > Phone.
2. Tap Call Blocking & Identification / Blocked Contacts > Tap Edit.
3. Tap the minus sign next to the numbers.