string = "NO PICK: hey there, hey you,NO PICK:hey there you, haha"
print( ', '.join([x.strip() for x in string.split(",") if "NO PICK:" not in x]).strip() )
c3RyaW5nID0gIk5PIFBJQ0s6IGhleSB0aGVyZSwgaGV5IHlvdSxOTyBQSUNLOmhleSB0aGVyZSB5b3UsIGhhaGEiCnByaW50KCAnLCAnLmpvaW4oW3guc3RyaXAoKSBmb3IgeCBpbiBzdHJpbmcuc3BsaXQoIiwiKSBpZiAiTk8gUElDSzoiIG5vdCBpbiB4XSkuc3RyaXAoKSAp