Protein shakes and weight loss/muscle gain?

I am trying to lose weight but also build muscle on my arms and abs. so far i do cardio every day for at least 30 minutes. i also do a strength workout 3 times a week and consume a protein shake afterword to help build muscle. my question is would it be better to skip the protein in an effort to take in less calories?...each shake is 300 calories.....Also, losing weight is slightly more important than building the muscle for me.