fired/no progressive dicipline and is a policy

I worked for a company for 18 months as a manager. I never received any written disciplines on anything. I was asked to turn in my resignation or except a termination for deligating someone to do my lessons. It was never shown to me in writing or did I read it anywhere that I was required to do these lessons. The new manager who took my place has not or is he doing the lessons. I had one of the most profitable operations, and my customers love me. I don't understand.

Wes

I forgot to mention I'm 47 years old