Can you make a field in the drop down inactive. So that you do not have to delete it?

If I understood you correctly, you want to make some of dropdown field options to be inactive (disabled). 

Only way to achieve this is to get full source code of your form and embed your form to webpage. Than you would be able to disable some options. 

Inside of this guide you can find how to get full source code of your form: 

http://www.jotform.com/help/104-How-to-get-the-Full-Source-Code-of-your-Form 

Here is an example: http://www.w3schools.com/tags/att_option_disabled.asp 

Other way is to delete dropdown field options. 

Hope this will help. Let us know if you need further assistance.