Here are instructions on how to perform a manual uninstall of the Delta series cards (including the RPC1):

Go to the Device Manager and remove any occurrences of the Delta in Sound,
Video, and Game Controllers and Universal Serial Bus Controllers.(you may
also see something called "unknown device" or "Multimedia Audio Controller"
which is usually listed under the category called Other Devices, which is
displayed with a yellow question mark Icon . If so, remove these as well).
Go to your "Folder options" control panel. On the view tab, put a mark
where it says "show hidden files or folders", also take a check out of the
box that says "hide file extensions for known file types" and take a check
out of " hide protected operating system files". Then hit apply and OK.
Next, go to your start/search/all files or folders. Scroll down to "more
advanced options". Check the first 3 boxes (search hidden files or folders,
search subfolders, and search system folders). Then scroll back up and in
the field name "all or part of the file name", do a search and delete for
the following:

*delta*.*
delteasi.dll
*rpc1*.* (if you are using an RPC1 card)
*oem*.* (a word or phrase in the file: Delta)
*oem*.* (a word or phrase in the file : Roland - if you are using an RPC1 card)

Next put a new or newly formatted floppy in your floppy drive. Once all the
driver files are deleted, go to the downloaded drivers, Double-click on
the .exe file and hit the finish button. You should now see all the file
extract over to the floppy.

Then go to device manager, highlight sound video and game controller,
right-click and select scan for hardware changes. You should then see the
new hardware wizard pop-up. Select "install software automatically" and hit
next. You will then see a message stating drivers have not passed windows
logo testing, hit "continue anyway" then keep hitting next until you get
finish. Hit Finish.