Unfortunately, I don't use Safari, but I suspect there is a way to clear out history and/or cache files. I actually just launched the version of Safari I have with OS 10.10.2, and under the Safari menu, there is a choice called "Clear History and Website Data". Not sure, though, what is available in the version you are using. Hopefully, someone else with more Safari experience can help you better. (I use Google Chrome, and there is a menu choice under the Chrome heading that offers me the opportunity to clear out various "things", including Cache files).