Please help me how to delete Mangle and Raw rules from my router.
How to remove builtin rules and why this exist ?
Remove all “fasttrack connection” filter rule under /ip firewall filter
Restart the router and the “buildin” rules will be gone
easy Script to remove all Fasttrack rules :
/ip firewall filter remove [find where action=fasttrack-connection]
I can’t also remove Filter rules.
Same message …
You need to remove filter-Rule #4 defconf:fasttrack
(aka. Blue symbole )
Fasttrack connection rule deleted and is fine.
Thanks for this solution 
And you understand that the purpose of fasttrack is not only to add rules that annoy you, but that it can also do something useful that you might want to have, right?