If you get banned permanently (doesn't matter which kind of ban) you are unable to play against bots, because a bot game is a VAC secured game. You can bypass this by setting -insecure as a launch option. If you are banned and you try to play against bots you will see this message after you got kicked from your bot session.
https://puu.sh/k5udM/5762aa6da8.jpg
As I already said, you are able to bypass this kick by launching your game with the -insecure launch option because this option prevents you from getting checked by VAC. You aren't able to play on VAC enabled Servers if you run your game with the -insecure launch option, but that shouldn't be a big problem if you are already banned :p
Step 1: Right click on CSGO in your steam libary and choose the "Properties" section.
https://puu.sh/k5usJ/d7b45e87bf.png
Step 2: Click on "SET LAUNCH OPTIONS...".
https://puu.sh/k5uuv/dd111b1ddd.png
Step 3: Write "-insecure" in the textbox and click on OK.
https://puu.sh/k5uxo/933bdeecc3.png
After you launched your Game with the -insecure launch option you'll see this message.
https://puu.sh/k5th5/13d139f03e.jpg
Congratulations, you are able to play against bots now.
Credit:Ridicc from r4p3