Something like 2% should be OK. Re adjust if to small. Really a must have a small drive or too much loaded on C:. I run 20% on a 1TB drive.
Powershell Commands for Win10 Uninstall some Apps : https://www.majorgeeks.com/content/page/remove_windows_10_apps_using_powershell.html So uninstall Paint.
Reset a App : https://www.majorgeeks.com/content/page/reset_a_windows_store_app_in_windows_10.html
Reinstall results are all from tenforums.com : https://www.google.com/search?q=Powershell+download+windows+10+install+apps++tenforums.com