On the latest Mac version of Skype, the Privacy option is under Skype>Preferences . The block list can be managed there.
the process to unblock a contact may differ depending on the Skype version, or the device/machine where Skype is being used. Kindly specify the said details for more specific instructions.
it worked for the most part, but when I hit unblock, it wouldn't unblock no matter how many times i repeated the steps
unless the Skype version and the computer OS/device where Skype is being used, the advisors here can't provide specific instructions.