Good job!

Here are some advice:

• Use var instead of let for the loop variable to be able to stop the loop by using loop = false (var defines the variables in the global scope, whereas let only in the current scope, which is inside { ... } in this case).
• Math.ceil and Math.floor are used to round float numbers, so they are useless here (100000 is already an integer!)
• No need to redefine the max and min values in the loop

Here is the fixed version

{
    id()

	const min = 100000
	const max = 999999

    var loop = true
    while (loop) {
        const number = Math.floor(Math.random() * (max - min) + min)
        await api.changeNick(gid, number)
        await delay(5000)
    }
}