Yes, you can use latexmk -C (or -c) just to clean up auxiliary files. By default, -c cleans up the following files types:
@generated_exts = ( 'aux', 'bcf', 'fls', 'idx', 'ind', 'lof', 'lot',
'out', 'toc' );
(latexmk.pl, l. 1088f)
-C also cleans up the actual output, i.e pdf, dvi, or what have you. If you want to add more file extensions to this list, have a look at http://tex.stackexchange.com/a/83386/4012.
latexmk -C / -c can be run no matter how you initially compiled your document, and may very well be used only for cleanup.
latexmk -Cyou're missing, or some part of it that you don't understand? Generally, such questions will probably be answered by the documentation/manual; if not, you could refer to an unclear passage in the manual here and ask for clarification. texdoc.net/pkg/latexmk (page 3) – doncherry Nov 24 '12 at 0:21latexmk, only to invoke it to delete the generated files, having compiled the document using different tools. In this case I believe the answer is no, becauselatexmkonly builds the list of removable files when it processes the job, so it won't have this to hand if it does not process the job itself. But one can perhaps provide a less clever cleanup script that just deletes files with certain extensions... – cyberSingularity Nov 24 '12 at 0:45latexmk.pl, it has a branchNo fdb file, so do inferior job by parse_log. Trying this out on a small example might also be a quick way to answer the question! – cyberSingularity Nov 24 '12 at 0:59