Blender Python script to deselect faces using thier index

deselect_faces.py

# give Python access to Blender's mesh manipulation functionality
import bmesh

# give Python access to Blender's functionality
import bpy

# add cube
bpy.ops.mesh.primitive_cube_add()
obj = bpy.context.active_object

# enable edit mode
bpy.ops.object.editmode_toggle()

# create a BMesh object to manipulate geometry data (must be done in edit mode)
bm = bmesh.from_edit_mesh(obj.data)

# make sure we can use the square brackets to access faces
bm.faces.ensure_lookup_table()

# deselect face with index 0
bm.faces[0].select = False
# deselect face with index 1
bm.faces[1].select = False
# deselect face with index 2
bm.faces[2].select = False

# disable edit mode
# bpy.ops.object.editmode_toggle()