"If I add a label to the front page (logged in front page) the html editor edits out some javascript that I want to be in the label.Where is the label file held so I can edit it manually?"Names of different things in moodle are sometimes difficult - I'm not sure yet what you really want to do but if you want to edit files that are used to create labels go to folder mod/label (the activity).
If the problem is that htmleditor cuts javascript it's normal behaviour of htmlarea - and you can disable htmlarea to be able to add those javascripts.
If you want to disable the filters you may need to edit some lib files from folder lib
If you have added a label from Add a resource - Insert a label then the label is saved to table mdl_label
If you have included a topic section from front page settings or edited some other section from boxes in courses the content is in mdl_course_sections
If none of these suggestions helped you could attach a screenshot of the problem...