The add-on you've installed from it (ITV) is harmless, but you can get/install the add-on from one of their mirrors without installing the repo.
Fiddling with cache settings is almost always bad and unnecessary. Unless your network or NAS/server are rubbish (in which case; fix the media source before blaming the playback device) there is no need to change something.
If you want to cheat installation and the SD card is a decent size you can just stop kodi and rename .kodi to .kodi-old and restart. I'm mostly interested in a clean system because a known state eliminates variables, and because anything we showcase upstream to Kodi or PVR add-on developers will only start with them asking for the same thing.