The server will not be able to remove files from a client browser. At a mininmum, it would require a signed applet. However, the cache directory location varies with operating system (and even w/in versions of the same OS). Then, most of the time the directory name is unknown / random. Moreover, depending on the variation of the client's operating system, the directory might not be sufficiently visible to the applet. Even assuming it is, files in the directory might be locked from removal, since the client browser must be running in the first place.