First, open the .def file using notepad.
Press Ctrl+F, search for this line and delete it.
; ===================== Billboards Start =====================
;----------
[BG Billboard Black Ops DLC]
;By Treyarch LOOOOL
type = normal
delta = 1,1
spriteno = 0, 10
layerno = 0
mask = 1
velocity = -11,0
;tile=1,0
start = 6100, 0
;----------
[BG Billboard Black Ops DLC 2nd Batch]
;By Treyarch LOOOOL
type = normal
delta = 1,1
spriteno = 0, 10
layerno = 0
mask = 1
velocity = -11,0
;tile=1,0
start = 79300, 0
;----------
[BG Billboard Shin Gouki Laundry]
;By Me
type = normal
delta = 1,1
spriteno = 0, 13
layerno = 0
mask = 1
velocity = -11,0
;tile=1,0
start = 4000, 350
;----------
[BG Billboard Black Lagoon]
;Credits to Gun0tradio
type = normal
delta = 1,1
spriteno = 0, 14
layerno = 0
mask = 1
velocity = -11,0
;----------
[BG Billboard Black Lagoon 2nd Batch]
;Credits to Gun0tradio
type = normal
delta = 1,1
spriteno = 0, 14
layerno = 0
mask = 1
velocity = -11,0
start = 79300, 0
;----------
[BG Billboard Chun-li]
;Credits to Flamekyo
type = normal
delta = 1,1
spriteno = 0, 16
layerno = 0
mask = 1
velocity = -11,0
start = 9688,0
;----------
[BG Billboard Chun-li 2nd Batch]
;Credits to Flamekyo
type = normal
delta = 1,1
spriteno = 0, 16
layerno = 0
mask = 1
velocity = -11,0
start = 9688,0
;----------
[BG Billboard Deadpool]
;Credits to Flamekyo
type = normal
delta = 1,1
spriteno = 0, 17
layerno = 0
mask = 1
velocity = -11,0
start = 12800,0
;----------
[BG Billboard Sonic]
;Credits to Gun0tradio
type = normal
delta = 1,1
spriteno = 0, 18
layerno = 0
mask = 1
velocity = -11,0
start = 14666,0
;----------
[BG Billboard Strider Hiryu]
;Credits to Gun0tradio
type = normal
delta = 1,1
spriteno = 0, 19
layerno = 0
mask = 1
velocity = -11,0
start = 17300,0
;----------
[BG Billboard Magneto]
;Credits to Flamekyo
type = normal
delta = 1,1
spriteno = 0, 20
layerno = 0
mask = 1
velocity = -11,0
start = 19200,0
;----------
[BG Billboard Nanaya]
;Credits to xX-Nero-Xx
type = normal
delta = 1,1
spriteno = 0, 21
layerno = 0
mask = 1
velocity = -11,0
start = 21000,0
;----------
[BG Billboard CM Punk]
;Credits to Gun0tradio
type = normal
delta = 1,1
spriteno = 0, 22
layerno = 0
mask = 1
velocity = -11,0
start = 24000,0
;----------
[BG Billboard Obito / Sasori]
;Credits to xX-Nero-Xx
type = normal
delta = 1,1
spriteno = 0, 23
layerno = 0
mask = 1
velocity = -11,0
start = 26400,0
;----------
[BG Billboard Troll-sama forum]
;Credits to Sal-Azul
type = normal
delta = 1,1
spriteno = 0, 24
layerno = 0
mask = 1
velocity = -11,0
start = 28600,0
;----------
[BG Billboard Graffiti]
;Credits to Flamekyo
type = normal
delta = 1,1
spriteno = 0, 25
layerno = 0
mask = 1
velocity = -11,0
tile = 1, 0
tilespacing = 53676,0
start = 30333,0
; ===================== Billboards End =====================
Save it and you're done!