The Torah prohibits men from removing their פֵּאוֹת.
The פֵּאוֹת area is the hair in the (almost) triangular area from the top of the ear to the forehead to the bottom of the ear.
According to some opinions, even cutting the פֵּאוֹת very close to the skin with scissors is forbidden.
Source: Kitzur Shulchan Aruch 170:1
Tuesday, 9 Iyar 5776 - 24th day of the Omer