Fundamentally, there are multiple definitions of "removable" - the classic one especially for CF cards is the one in their ATA identity ("passport" in Victoria), which is generally fixed to "fixed" for industrial cards, always "removable" for most every retail one, and can't be changed (outside of very targeted firmware mods like atcfwchg for at best a couple years' worth of Sandisk's production, or a handful of models that automatically becomes "fixed" for IDE operation);
and being actually hotpluggable, like being on an USB interface!
(even IDE is hotpluggable, actually - it's just that pretty much no OS is designed for that, but low level direct disk access software like MHDD won't complain 😀 )
I think, but am not sure at all, that in 9x you can tell apart the former from their icon (and the fact they'll reject multiple partitions: superfloppy or single MBR partition only - of course you must deal with this with 3rd party software!)
The 2nd definition is relevant to the extent you must configure the bios correctly for your card - ignore any "ATAPI removable" options and set it up like a traditional HDD (auto or manual), which of course will highlight any problems it may have with your card…
(Most HDDs over 8 GB will list that as their maximum CHS capacity, but most CF cards declare their real capacity, and apparently this really screws up int13 disk access in my Igel M310C)