This free tool will spoof and change your MAC Address and can make you bypass the Roblox API Ban System.
Tutorial
Unistall Roblox using IObit Unistaller
Download Technitium MAC Addres Changer
Starting MAC address changer will list all available network adapters.
Select the adapter you want to change the MAC address. You will get the details of your selection below.
In the Information tab, find the Change MAC Address frame. Click Random MAC Address button to fill up a randomly selected MAC address and click Change Now! button.
Done! You can now join the game you're banned with another alt and you're gonna be unbanned.
NOTE: To restore the original MAC address of the network adapter, select the adapter, click Restore Original button in the Change MAC Address frame.
Credits for the method to SirMeme