Can my employer fire me without any performance management plan at all?

Yes, however it depends on how they decide to end your employment. If they are offering you the notice or compensation you are entitled to, then they can effectively end the relationship at any time with no performance management required. 

If however they attempt to terminate you with cause, contact our office right away. There are very few possible situations where such a termination would be upheld by a court, especially without any sort of investigation. Not only are you likely owed reasonable notice of termination, but your employer may be liable for some serious additional damages for how they’ve carried out this process.