How to change the logo to another builtin logo ?

[notV3NOM]

I dont like how the current ubuntu logo looks and wanted to change it to the ubuntu_old builtin logo. I cant figure out how to do it

"logo" : {
    "type": "builtin",
    "source": "ubuntu_old"
}

Should I just use an image ?

[CarterLi]

Removing "type": "builtin" should work

[notV3NOM]

It did , thank you