Is it possible to edit the contents of a drop down based on a users selection of another field ?

I am not sure if I have understood your question correctly. Do you mean to say that you want to populate or add remove items of dropdown field based on the selection of another field?

Unfortunately no it is not possible to dynamically add / remove items of dropdown field. I would suggest you to please add multiple dropdown question and take advantage of our conditions feature to show / hide appropriate dropdown question based on the selection of another form field. 

Hope this helps.

Do get back to us if you have any questions. 

 I would recommend using the Dynamic Dropdowns widget:

It might be a bit confusing with the indentation method the widget is using, but it's relatively faster than making specific conditions for each option (especially if you have more than a few).

Here is how it looks: 

Depending on the way you have your form setup this could eliminate the field that would decide the contents of the drop-down menu, so that could be a plus as well.

If you decide to go this route and need some help setting up the options, feel free to ask, we would be more than happy to help!