The clutch in this 1983 R80ST is the same as the one used in the 1983 R100RS that I rebuilt and converted to an RT model. You can see the procedure I used to remove the 1983 R100RS clutch here.
I summarize what I found on the 1993 R80ST in this document, which has links to sections of the 1983 R100RS clutch removal document.
I also shot a short video of the work I did on the R80ST.
VIDEO: 1983 BMW R80ST Clutch Removal
The clutch was a bit rusty and grungy. I plan to replace it with one donated by Euro MotoElectrics.