I think the only way is to move the folder where they're installed. Of course, that means you'd have to put them back when you want to use ProTools.
In the past, if VST plug-ins were causing the crashes, you could launch Pr multiple times until the crashes stopped. Each time a VST plug-in causes a crash, Pr blacklists that plug-in. When all the problem plug-ins are blacklisted, the crashing should stop.
Jeff