Hi, I just want to be able to turn off all category and group image support. I don't need default images either. Just text. Is this possible?

You can edit the templates to remove logo display. GJ template files located at the below folder.

components/com_comprofiler/plugin/user/plug_cbgroupjive/templates/

Your changes will be lost on upgrade if you edit the defaults though. GJ is designed to allow overrides. So you could for example copy the default folder, rename it, delete any file you've no intention to change, then change the remaining you want changed. Once done navigate to GJ configuration and select it as your new template. Any files you don't supply it'll pull from the default template.

In fact I wouldn't mind turning off categories all together and just having all groups in one place if that's easily done? if not that ones not a big issue for me.

Not possible to disable categories. No plans to allow disabling them either.