This is a simple module to strip categories from wikitext. For example, if passed the code "<nowiki>foo[[Category:Some category]]</nowiki>", it will return only "foo".
The module properly handles categories escaped with the colon trick, categories whose names include invalid characters such as ">", and categories that are surrounded with nowiki tags. However, it does not support complex wikitext such as nested links or magic words like <nowiki>__TOC__</nowiki>. Even so, it should still remove the vast majority of categories from any given wikitext.