Are you sure you downloaded TinkerTool System 2 and not the freeware TinkerTool? In the TinkerTool System 2 main menu the top row of icons is labeled "System Maintenance" the second icon from the left looks like a blue recycle bin and is labeled Caches. Click on that icon and there are three tabs
  1. Application-Related caches
  2. Font Caches
  3. Startup Driver Cache
Under the first two there are multiple options for caches that are to be deleted. The options are pretty self-explanatory but if you have more questions TinkerTool System Help has detailed explanations of each.

SInce I have registered copies of TinkerTool System 2 installed on all my Macs, I don't know which, if any, of the functions are disabled in the trial version.

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein