You can do this to add all the phone numbers to the first record (comma separated, you can add a parm to change this to a slash instead but this would be an even worse idea)
UPDATE test a INNER JOIN (SELECT name, address, GROUP_CONCAT(phone) AS AllPhone, MIN(id) AS MinId FROM test GROUP BY name, address) b ON a.name = b.name AND a.address = b.address AND a.id = b.MinId SET a.phone = b.AllPhone
Then delete the others with something like this
DELETE a FROM test a LEFT JOIN (SELECT name, address, MIN(id) AS MinId FROM test GROUP BY name, address) b ON a.id = b.MinId WHERE b.MinId IS NULL
Note that this going to give you a delimited list of phone numbers for a name / address which is a major pain to deal with in future, and a sign of a badly designed database.