<sshexec host="${remote.host}"
username="${remote.user}"
password="${remote.pass}"
trust="true"
command="rm -rf ${remote.webapps.path}/ROOT*" />
You can read about more detailed examples here.
To add this feature to your ANT installation, you need to download the JSch – Java Secure Channel library and include the jsch jar file into ANT classpath (i.e. in your ANT_HOME/lib/ or — if you’re using an Eclipse — into Eclipse Ant classpath).
I found this feature quite useful as it reduced time I needed to build and deploy an application.