How Do I Fully Flush Cached Redirects From Safari?
Based on quanta’s answer:

I wasn’t able to use launchctl unload /System/Library/LaunchAgents/com.apple.nsurlstoraged.plist because I have System Integrity Protection enabled:

$ launchctl unload /System/Library/LaunchAgents/com.apple.nsurlstoraged.plist
/System/Library/LaunchAgents/com.apple.nsurlstoraged.plist: Operation not permitted while System Integrity Protection is engaged


However I was able to work around it by doing the following:


killall nsurlstoraged (stops your user’s nsurlstoraged process; I actually ran sudo killall nsurlstoraged, but I suspect it isn’t necessary to stop the system’s nsurlstoraged as well, since the cache is in the user Library folder)
rm -f ~/Library/Cookies/HSTS.plist (deletes the HSTS cache)
launchctl start /System/Library/LaunchAgents/com.apple.nsurlstoraged.plist (restarts nsurlstoraged)