Can I stop using Minoxidil after prp + acell treatment?

There haven't been any clinical studies to show effectiveness of this combination of Minoxidil and PRP, but I'd suggest continuing to use the Minoxidil as it works differently than PRP to simulate hair follicles and help with hair growth. 

Minoxidil is intended for continued use. I would recommend continuing using it consistently and as directed for your hair loss. 

In my opinion it is best to use the medication with the PRP & A-Cell. This will give you better results as well as you will still need to have PRP maintenance after that, usually I suggest one treatment every 6 months, depending on results and your expectations. Please consult a professional in your area.