let me put it like this: an uninstaller of that type you know from OSX or windows is not needed in MacOS9.
the majority of OS9 apps are one executable or one folder with one executable in it, and to "deinstall" it, you move it to the trash.
regarding your extensions issue, you are worng when you think that turning off an extension will not prervent it from conflicting it with others. it will. the extensions controlpanel simply moves the driver from the the driver folder to a folder called "system extensions off" or similar, and things in this folder are not loaded. that is the idea behind it.
if you want to remove a driver from MacOS9, i know no faster way than doing it manually.
in the apple menu there should be a link to "control panels".
go there.
then click
command-alt-arrowUP and you are in the root of the
current system.
then type "s" to quickly find "
System Extensions". open it.
type "
t" to quickly find your tascam driver. select it.
type
command-delete to move it to the trash.
takes 5 seconds. and you dont even need to know where your system is located or in which of you three you just booted.
works best if your system folder window is set to list view.
...
the best thing you can do when you are new to OS9 (or when you do looots of stuff in it) is to change the
label color of everything apple installs by default into
/system extensions and
/controlpanels by default to green.
so now whenever some program installs a new file into
/system extensions or
/controlpanels - these are the two places where driver software
always ends up in - you can easily find these new items by going for the files with no label color. in list view this can be a nobrainer, because you can have all new files on top. it could not be easier.