Reference: I’laam al-Mu’aasireen bi-Fataawa Ibn ‘Uthaymeen – Page 217
Question: With regard to the hairs [which grow] below the bottom lip, are they regarded as part of the beard?
Response: These hairs are called “al-‘anfuqah” and are not regarded as part of the beard, [however] it is preferrable to leave them as they are unless they harm the person.