All of the info on the Gov.uk points to this login page as the right place to be in order to change information about your company:
https://ewf.companieshouse.gov.uk//seclogin?tc=1
So if that's the route you've already taken, I'd expect there to be an option to do so at some stage.
(I've not run a limited company myself since the days when quill pens were regarded as modern technology so, regrettably, I can't advise you directly from personal experience of using the online service. Sorry)