Pressero Version 5
For Pressero version 5 there are two pages that you can navigate your browser to that will clear cache. For example, sitename.accountname.v4.pressero.com/flushcache and then hit return.
This page will clear the cache that exists between client (your website) and custom skinning files. This only needs to be done when changing layout files such as any file ending with .txt or .inc.
This page will ask you to hit a button. The button will clear the cache between client (your website) and any data in Pressero admin. So if you make a change to a products data and want to see it on the site right away use this page.
Pressero Version 6
Version 6 of Pressero rolled both /flushcache and /clearcache into one. Now in order to clear the client to admin cache and the client to custom skin cache simply navigate your website to this page (yourwebsite.com/clearcache). Further changes to how caching work now requires that you navigate to /clearcache for any file change in your custom skin, not just layout files.