The easy solution is to just disable drilldowns from the view altogether. You can achieve this by configuring the panels in the UI or by adding proper parameters in the AdvancedXML.
However, if you want to disable drilldowns for just a subset of users, you will probably have to code ad-hoc javascript in a custom application.js file. You can find examples and reference code on dev.splunk.com. Here are some useful infos customization examples, application.js.