Currently, we only have one option for a doctor's white coat in our character creator for the Whiteboard Animation style. While it includes a stethoscope, which is very useful for some types of doctors, others, like dentists, for example, don't necessarily use this tool. Unfortunately the stethoscope cannot be removed as it is part of the coat itself but I've recently shared this feedback for an enhancement requests with our team.
Since these requests may take some time to be taken into consideration and/or implemented, I've found a pretty good workaround in the meantime.
You can use the shirt option shown below which has long sleeves and a collar. This can work well for a dentist or pharmacist, for example, as shown in the second image. The shirt is available for both female and male characters.