When you delete the interface name in Junos this removes every reference to the interface as you have seen. This is used when you have a lot of interfaces that you simply don't use on a device and you don't want them to show up at all in any of the review and monitoring commands as you have seen.
You can restore the interface by simply typing the full name instead of using autocomplete.
To remove all configuration from an interface but keep the interface itself listed you can delete from the interface down in the heirarchy.
edit interface ge-0/0/3
delete
Junos is like a directory structure and edit works like change directory to put you at a certain level. When you issue the delete at this lower level it keeps the interface ge-0/0/3 but removes all ocnfiguration assigned to that interface.