Awhile back I installed the Oracle 10g XE database on my dev machine. Since then, I installed Application Express over top of the XE installation. In other words, it's APEX running on 10g. I found I don't really need APEX after all (it's turned out I'm developing in ASP.NET and Oracle instead), and I recall having more of a GUI to manage the XE 10g instance BEFORE I installed APEX.
Can I remove APEX while leaving my original XE installation? I tried to re-install the original XE, but I didn't see a way of doing this without installing a new HOME (which I'd rather not do; it confuses me). TIA.
Oracle XE comes with APEX installed, along with a ( from memory ) APEX based XE management tool. What it sounds like you actually did was was upgrade/over install a newer version of APEX, then remove APEX all together.
Probably the easiest thing to do would be to backup your user schema's using exp or expdp ( data pump ) , uninstall XE, reinstall XE and then import your user schema's. This will get XE back to how you want it.