Redirect permanent /subfolder/ /This would redirect www.yoursite.com/subfolder to www.yoursite.com.
Then later on you to add proxy config:
ProxyPass / http://localhost:8080/site/
ProxyPassReverse / http://localhost:8080/site/
ProxyPassReverseCookiePath /site /
But after that your redirect fails. It turns out that ProxyPass config overrules Redirect. Add exclusion to the ProxyPass to fix this:
ProxyPass /subfolder !
ProxyPass / http://localhost:8080/site/
ProxyPassReverse / http://localhost:8080/site/
ProxyPassReverseCookiePath /site /
Note that the exclusion is before others.