You cannot toggle PR proxies in AE. As far as AE is concerned, it's just another layer container and AE has no knowledge of the internal mechanics. It would be no different the other way around. So if you want to change those settings, you have to go back to Premiere, clean out the caches and toggle the settings, then refresh AE. This being a clunky workflow, it is generally better to render out intermediate sequences from Premiere and assign them as proxies directly in AE while importing the original sequence at full quality.