Find server.xml at $CATALINA_BASE/conf/server.xml
Find appBase
attribute in <Host>
element
by default it will be something like :
<Host name="localhost" appBase="webapps ...>
Change appBase to your required path. There are different way people put it, but I use
/c:/myfolder/newwebapps
Remember, no slash at the end, but at start. Also note it's direction as well.