I was told I couldn't get promoted at work due to my age. Is there anything I can do?

I was being trained as a manager at a local pizza place. Im 45 and wanted to get to a GM position and to eventually franchise my own store. I have many years of experience. I was in the middle of being trained when a New GM took over and told me he wanted a younger management team and that he was gonna cut my hours to 10 to 15 hours per week unless i wanted to deliver pizza. I was working 40 hours inside. What can i do? I was so devistated, i walked out.