How to undefine CONFIG_CMD_NET?

I can not find this configuration defined anywhere in my include/configs/.h file and includes, nor in configs/_defconfig and it is still defined in .config file after configuring u-boot. I am seeing this configuration defined in tools/Makefile. Is it default? Should I use #undef in me include/configs/.h or CONFIG_CMD_NET=n in configs/_defconfig? What is better?

Solution

This configuration option is described as

CONFIG_CMD_NET:

   Network commands.                                 
   bootp - boot image via network using BOOTP/TFTP protocol   
   tftpboot - boot image via network using TFTP protocol  

   Symbol: CMD_NET [=y] 
   Type  : boolean                                
   Prompt: bootp, tftpboot  
     Location:   
       -> Command line interface  
         -> Network commands 
     Defined at cmd/Kconfig:403  
     Selects: NET [=n]

You can disable CMD_NET using make menuconfig.

Command line interface
    Network commands
        [*] bootp, tftpboot

You can also hardcode your configuration in your board's config file, as suggested in the README file:

EXAMPLE: If you want all functions except for network support you can write:

   #include "config_cmd_all.h"
   #undef CONFIG_CMD_NET