This is a Common vow undertaken by devotees at Tirupati.

The objective behind tonsuring (shaving one's head for the Lord) is to demonstrate that he/she completely surrenders his/her ego at the feet of the Lord. Pilgrims can have their heads tonsured at the Kalyanakatta (opposite the Annanadanam Complex). There are seventeen sub-centers for tonsuring. Pilgrims can also request to be tonsured at the cottages where they are staying.