Why won't my sprites delete properly with the kill() function?

Question

I am creating a game where you shoot enemies in a top-down format. My bullet and enemy function properly in every aspect except where it has to delete itself. I have hooked it up to where if the bullet collides with the enemy or 5 seconds have passed, the bullet would delete itself. It does do that, except the code continually iterates to create a sprite and kill it as the bullet moves for some reason, and still shows the bullet on the screen as if nothing is happening to it. Can someone tell me why the code is iterating the creation of a bullet and the deletion of it so many times?

-------- CODE --------

method in player class

def shoot(self):
    pos = pygame.mouse.get_pos()
    pos += camera_group.offset
    click = pygame.mouse.get_pressed()
    if click[0] and not self.shooting:
        self.shooting = True
        # create bullet instance if player shoots
        bullet = Bullet(self.rect.centerx, self.rect.centery, "bullet", pos, camera_group)
        bullet_group.add(bullet)

    if not click[0]:
        self.shooting = False

bullet class

class Bullet(Entity):
def __init__(self, x, y, image, pos, group):
    super().__init__(x, y, image, group)
    pygame.sprite.Sprite.__init__(self)
    # creating and scaling image
    self.image = pygame.transform.flip(self.image, True, False)
    self.image = pygame.transform.scale(self.image, (32, 16))
    # creating rect
    self.x = x
    self.y = y
    self.speed = 8
    self.mousepos = pos
    # calculating angle of bullet
    self.angle = math.atan2(pos[1] - y, pos[0] - x)
    self.angle_deg = (self.angle * (180 / math.pi))
    self.image = pygame.transform.rotate(self.image, self.angle_deg * -1)
    # calculating vel_x/vel_y
    dx = self.mousepos[0] - player.rect.centerx
    dy = self.mousepos[1] - player.rect.centery
    total = abs(dx) + abs(dy)
    self.vel_x = (self.speed * (dx / total))
    self.vel_y = (self.speed * (dy / total))
    # setting variable to store time of bullet creation
    self.start_time = pygame.time.get_ticks()

def update(self):
    if pygame.time.get_ticks() - self.start_time > 50 and len(bullet_group) >= 1:
        bullet_group.sprites()[0].kill()

    elif self.rect.colliderect(enemy):
        bullet_group.sprites()[0].kill()
        enemy.kill()

    else:
        # movement
        self.x += self.vel_x
        self.y += self.vel_y
        self.rect.x = int(self.x)
        self.rect.y = int(self.y)

Answer 1

Don't kill the first bullet in the Group , just delete the bullet object itself:

bullet_group.sprites()[0].kill()

self.kill()

method update in class Bullet :

class Bullet(Entity):
    # [...]

    def update(self):
        if pygame.time.get_ticks() - self.start_time > 50 and len(bullet_group) >= 1:
            self.kill()

        elif self.rect.colliderect(enemy):
            self.kill()
            enemy.kill()

        else:
            # movement
            self.x += self.vel_x
            self.y += self.vel_y
            self.rect.x = int(self.x)
            self.rect.y = int(self.y)